December Fitness Challenge
Daily fitness challenge for the month of December focused on the core.
Daily Challenge
As a functional fitness coach of several years, I run a community-based fitness group outside of my gym. We discuss goals, meet weekly for outdoor workouts, and tackle a new daily challenge each month.
The intent of these daily challenges is to create productive habits and induce both mental and physical adaptations. The at-home exercise is never more than ten minutes - often less. Short, achievable tasks provide an opportunity to still earn the day when your plans get disrupted.
Consistency will always produce better and more lasting results than intermittent intensity.
Anyone can find a few minutes to do something beneficial for themselves.
That’s all you need to begin seeing progress.
The Specific Adaptation to Imposed Demands (SAID) Principle is an exercise physiology concept that demonstrates the more you do anything, the better you get at that specific thing.
The body’s ability to physiologically adapt and maximize performance based on what we consistently put it through is amazing. Even more impressive is the mind’s plasticity in response to stress.
Machine learning for humans.
Fitness serves as a vehicle for resilience training, with the physical benefits secondary to the mental skills developed.
Showing up daily isn’t easy but it’s how lasting change is formed.
Enhance resilience by consistently embracing self-created challenges.
December Daily Challenge: Waistline Refiner
This is the time of year when most slip.
Movement slows bringing momentum to a halt.
Nutrition fades while indulgence intensifies.
Pleasure pervades while discipline disappears.
Last year, Michael Easter put out powerful article that demonstrates the potential impact the holidays can have on your health.
Bottom line up front: The average person gains 1 to 5 pounds between Thanksgiving and New Year’s and they typically don’t lose it.
Are you waiting until the new year for a resolution?
The data are clear on resolutions: 92% of adults do not follow through on resolutions with the majority quitting in the first few months.
December is the month to implement a daily challenge - to set an intention that influences the choices you make throughout the riskiest time of year. Resolutions in January won’t reverse the self-induced degradations of the holiday season for most.
Now is the time to act.
Prevent loss of progress during this month by proactively implementing productive systems today.
The goal is to incorporate a daily challenge aimed at the area of our body that takes the biggest hit during the holidays. Doing a core workout daily can bring awareness to your other choices throughout the month so discipline isn’t completely lost while hopefully enjoying time with loved ones.
Challenge your core to consciously construct your other choices.
Mindful decisions this time of year matter.
Waistline Refiner
25 mountain climbers (2-count)
25 right side plank hip dips
25 cobra dogs
25 left side plank hip dips
25 bird dogs (right arm/left leg)
25 bird dogs (left arm/right leg)
The core is more than just the abdominal muscles in front of your stomach. The core also involves multiple muscles of the sides (obliques), back (posterior chain), and pelvis (pelvic floor, hip flexors, glutes). Workouts like the Waistline Refiner target more areas of the core compared to the standard sit-up.
Modifications for all levels are offered below.
Just a few minutes of daily work over the course of a month will cause multiple adaptations in your mind and body.
Stacked skill development opportunity for functional fitness and developing the skill that is resilience.
Technique & Modifications
* Watch videos for technical demonstration and discussion. The written steps can help add detail to the micro-movements as needed *
Mountain Climbers
Mountain climbers are a classic core-strengthening exercise that simultaneously challenge your cardiovascular system, stability, and coordination when done at a higher intensity.
Starting Position:
Hands plank - place your hand directly under your shoulders and your feet shoulder width apart to enter the high plank position
Engage your abs, back, and glutes
Execution:
While maintaining balance in the plank and attempting to keep your hips level, begin by driving one knee toward your chest
As your first leg is returning to the starting position, drive the other knee forward so there is a brief moment where neither foot is on the ground as if you are running
That is one rep
Modification:
Perform the movement is a slow, stepping motion rather than running
Forearm plank - with legs straight, position your forearm on the ground facing the direction you are facing with the elbow directly under your shoulder/head
Low knees plank - bend your legs and allow your knees to support your weight
The further away your knees are from your arms, the more difficult the exercise is
Combine forearm and knees plank for further modification as shown in the video
Side Plank Hip Dips
Side planks are an excellent exercise that enhance core strength and shoulder stability. Adding in a hip dip and lift targets the oblique muscles creating a fantastic movement to improve the strength and health of the often forgotten side muscles.
Starting Position:
Side hands plank - with legs straight, position your extended hand on the ground
Hand should be directly under your shoulder/head to support your upper body
Feet can be stacked or staggered for extra stability
Back and neck should be aligned
Execution:
Slowly lower your bottom hip toward the floor in a controlled manner
Let the hip gently touch the floor or get as close as you can without losing balance
From the bottom position, drive the hip back up to or slightly beyond the starting position
That is one rep
Modification:
Side forearm plank - with legs straight, position your forearm on the ground facing the direction you are facing with the elbow directly under your shoulder/head
Side knees plank - bend your legs and allow your stacked knees to support your weight
Combine side forearm and knees plank for further modification as shown in the video
Cobra Dogs
A combination of the downward dog and cobra pose, cobra dogs enhance mobility, flexibility, and strength in the core. While downward dogs also support flexibility in the hamstrings, calves, and shoulders, the emphasis of this unique movement is repetitive elongation and compression of the abs and back.
Starting Position:
Hands plank - place your hand directly under your shoulders and your feet shoulder width apart
Engage your abs, back, and glutes
Execution:
Raise your hips toward the sky while driving your head down between you shoulders to look at your toes
Focus on maintaining a straight spine while you either keep your legs straight or slightly bend at the knees
Once you complete a downward dog, drive your hips to the ground as you begin to look up
Round your back and stretch your abs as your thighs and hips hover above the ground
That is one rep
Modification:
Perform the movement from the low knees plank position
Perform the movement from the forearm plank position
Perform the movement from the forearm and low knees plank position
Bird Dogs
Bird dogs are a fantastic exercise that strengthen the core, particularly the posterior chain/lower back muscles while enhancing spinal stability and balance.
Starting Position:
Tabletop position - place hands directly beneath shoulders and knees directly beneath hips
Back straight with neck aligned by looking at the ground
Execution:
Stretch one arm forward and the opposite leg straight back
Once the arm and leg is extended to the height of your torso, contract both limbs and connect them at the knee and elbow
That is one rep
Modification:
Lift your arm and leg off the ground as high as you can without strain and then contract both as close as you can to touching
Lift just your leg off the ground as high as you can and then contract toward your opposite arm for one rep
Lift your arm off the ground as high as you can and then bring your elbow toward your opposite hip for one rep
For all movements:
Maintain neck alignment with the spine
Avoid cervical strain and sagging of the shoulders
Keep your shoulders aligned with the hands or elbows on the ground
Focus engagement in your abs, back, and glutes throughout
Progression Guide
For Beginners:
Use forearm and/or bent knee modifications and practice each movement going slow
Complete smaller sets of each movement (such as five sets of five reps each)
Decrease repetitions for each movement overall
Start with modifications that allow you to complete the challenge in less than ten minutes
Progressively increase difficulty until you are able to complete the entire workout unmodified and unbroken (preferably in five minutes or less)
Assisted work causes necessary adaptations for skill development too.
For Intermediate/Advanced:
If you can do an unmodified, unbroken Waistline Refiner and feel pretty good, progressively increase your rep count to fifty or do two sets back-to-back
Either can be done in under six minutes if you’re able to go unbroken
Complete one Waistline Refiner set followed by the Ab Stacker, Trunk Transformer, and Core Conditioner for a full core workout (goal is less than fifteen minutes)
Ab Stacker: 25 supine sit-ups, 25 legs bent sit-ups, 25 crunches, and 25 leg raises
Trunk Transformer: 25 star crunches, 25 side v-ups left side, 25 supermans, 25 side v-ups right side
Core Conditioner: 25 large flutter kicks, 25 leg scissors, 25 Russian twists, 25 leg pendulums (2-count each)
Even if you do this workout for the entire month with modifications, you will still cause multiple adaptations in your core to enhance performance and decrease injury risk.
The Waistline Refiner combined with the Ab Stacker, Trunk Transformer, and Core Conditioner allows you to comprehensively train your core with just body weight.
Progressively reach a level of competency with the variations offered here. Once you become comfortable executing in a given way, expand the challenge.
As always, compete with yourself yesterday.
Progressive improvement is the goal.
Quality of movement is far more important than quantity of reps or time. Use modifications to develop the adaptations needed to perform the variations safely with good form.
Show up and do your best.
Battle your internal resistance and get that small win.
Everything, including your choices around the holidays, feels easier when you occasionally make things a little harder on purpose.
This is self-care.
The primary purpose of a daily, intentional challenge - training the skill that is resilience physically, mentally, and spiritually.
Get Ready
I’m posting this a day early so everyone, including my international friends, can prepare to start strong on day one.
Track your reps and modifications only to set a goal for the following day. The outcome doesn’t matter as long as you show up and put out.
Consistent effort leads to improved performance over time.
How will you respond when you don’t feel like it?
These are the days that matter most.
These are the days that change you.
These are the moments you see what you’re made of.
This is how resilient mental states are forged.
Embrace the challenge of discipline to optimize the skill of resilience.
Deliberate discomfort daily can lead to improved comfort elsewhere forever.
By the end of December, if you consistently complete this challenge regardless of modifications, your core strength, spinal health, shoulder stability, balance, coordination, and resilience will be improved.
Use a brief fitness routine to insert control and success into every day.
Self-care through self-challenge.
A few minutes a day can change your life.
*Special Offer*
Join our community and earn a group call with other members at the end of the month to discuss progress and other opportunities for improvement:
Complete the challenge for more than half the month.
Bonus offer available for those who complete it every day.
In our community chat, we’ll hold each other accountable by posting a ✅ after completing each day’s challenge. Timing and modifications don’t matter—just show up and do your best.
To claim your special offer(s), share your story at the end of December:
Share a reflection on your progress (either in the community chat or privately with me) and then I’ll confirm your ✅ count.
Join our community, and let’s improve together.
Disclaimer:
The content provided is intended for general knowledge and informational purposes only and is not a replacement for medical advice. Always consult with a qualified healthcare professional prior to making any decisions or changes relating to your health. Kyle Shepard is not responsible for any adverse effects resulting from the use of the information in this publication.
Brilliant! Avoiding a pound of weight gain (rather than trying to lose it) and building core strength are among the top health (both physical and mental) prescriptions I can think of, especially when combined with your writing about “resilience”. Thanks for bringing so much actionable wisdom to this platform and its readers, Kyle! 👏
Cobra dogs are awesome, I’ve came across a dive bomber or Hindu pushup and a Tyson push up but this is like a fusion of the two I love it.
Also for the record, if we are ever in a special operation with code names. I want my code name to be Cobra Dog. Over and out!