Walk for five to 10 minutes at a comfortable pace, noting how far you go. Next time, walk the same amount of time, but aim to cover more ground. After 10 minutes feels easy, keep progressing until you ...
Follow along with trainers Jacqueline Kasen and Gerren Liles in the workout video above, or if you're ready to HIIT it solo, read the instructions below for a self-guided workout.