Duration: 33 minutes
A lower-body rep-goal session: reach 50 total reps per exercise in as few sets as you can, from two to five. Start with a pyramid, adding a couple of reps each round, and over time push toward fewer sets with more reps. When you can do 50 reps of an exercise in two sets of 25, swap it for a harder variation, for example half squat to deep squat to jumping squat. No equipment required.