Strong Body, Fit Body with Erin O'Brien A smooth-flowing workout that mixes traditional moves with newer balance and compound exercises. It’s a motivating, time-efficient blend that challenges your muscles in varied ways. The program is exceptionally fluid — each move just naturally transitions into the next. Many sequences also integrate multiple, complimentary techniques (e.g. a reverse lunge with an overhead press strengthens your upper and lower body while also improving balance). Erin O’Brien’s cuing is both friendly and informative — lots of technique tips and harder/easier options. Requires 3 to 5 lb. dumbbells.