This was pretty hilarious! I am pretty sure my feet never came close to my rear end! But as part of the goal was to stretch your hamstrings, I did some standing hamstring stretches by bending my knee and grabbing my foot from behind , stretching the thigh back, and stretching the hamstring in the process. Coupled that with balancing (or attempting to balance) by lifting the opposite arm straight up (I call it the Stature of Liberty pose). This is a stretch we use in Zumba, but I have yet to master it. Getting better though. No, I doubt if I'll ever be able to kick my own butt while jogging, and I'm not sure I'd really want to, but these adaptations helped me to accomplish the purpose of the challenge!
"Jog in place for 30 seconds, bringing your heels as close to your backside as you can"