Because I didn't complete my Day 20, I redesign Day 21 to catch up what i missed yesterday.
Original design of Day 21 = 200 punches + 200 bicycle
My Day 21= 15 burpees + 2x30s planks + 100 bicycles (alternate between 20 bicycles and 20 bicycle crunches) + 200 punches + 100 bicycles (alternate between 20 bicycles + bicycle crunches) + 1x60s plank + 15 burpees.
It's fun to do the workout with so many variety. But I have to pay the price. Now I'm resting in my garden. My core muscles are crying in pain.
Lesson of the day: Never procrastinate! or you will have to pay the price.