You can do this with...
A ___mile run
A 1/2 mile sprint (or any distance for that matter)
A certain circuit workout that you love
Your favorite running trail
A flight of stairs
Your own fitness obstacle course
Day #20: 20 Sumo SquatsYou can do these with or without weights. Open your legs up wide, with your knees and toes facing out. Squat down as low as you can, and then stand back up and tuck your hips under. If you want to hold a kettle bell, some dumbbells, or a bar to make it more difficult, go for it!