Haven't had time for regular workouts? Fear not, says David Kirsch, Heidi Klum's trainer. To quickly—albeit temporarilytighten your jiggly areas before a big date, he suggests a mini circuit. "Five minutes before you get in the shower, do 10 squats, 10 sumo lunges, and 10 push-ups. You'll feel firmer and more confident, and stand taller."