1. One-Rep Sit-Ups
Lift your torso one inch at a time, holding steady for ten seconds before moving again, until you're fully upright in a typical sit-up position. Repeat eight to ten times.
2. Power Planks
Hold a basic plank for ten seconds. Widen your stance and lift one leg for a count of ten, then switch. Repeat three times.
3. Pulsing Lunges
Step forward with your left leg, then bend your right leg until your knee is an inch from the floor. Lift yourself up one inch, then lower back down without letting your knee touch the floor. Do 45 quick reps and repeat on other side.
Courtesy of Pete Cerqua, author of High Intensity Fitness Revolution for Women (Skyhorse).