This one's just as much a test of your mental toughness as it is physical. Start with 21 reps of each, then 20, 19, 18... all the way down to 1 each. Rest as little as possible. Record your time and report back. YOU GOT THIS!
Start with 18 reps of each
Start with 15 reps, sub in knee pushups and situps
(*For an extra challenge, swap out Burpees for Pushups!)