I want you to have a lean six-pack, cut arms, ripped shoulders, and toned legs. And I’m going to make sure you get them in only 21 days! So I’m going to challenge your body with something new, each day of the week. You’ll be doing steady-state aerobics, resistance training, and explosive power moves to target every inch of your body. But every 30-minute workout has a modifier, so you can gradually build the intensity.

• Autumn Calabrese