Crunches: Lie on your back with your knees bent and feet flat on the floor. Place your hands behind your head and lift your shoulders off the ground.
Planks: Get into a push-up position with your forearms on the ground. Hold this position for 30 seconds to 1 minute. Repeat for 3 sets.
Russian twists: Sit on the ground with your knees bent and feet flat on the floor. Lean back slightly and lift your feet off the ground. Twist your torso to the right and then to the left.
Bicycle crunches: Lie on your back with your hands behind your head. Lift your shoulders off the ground and bring your right elbow to your left knee. Repeat on the other side.
Leg raises: Lie on your back with your hands under your hips. Lift your legs off the ground and hold for a few seconds. Lower your legs back down.
Mountain climbers: Get into a push-up position. Bring your right knee to your chest and then switch to your left knee.
Reverse crunches: Lie on your back with your hands under your hips. Lift your legs off the ground and bring your knees towards your chest. Lower your legs back down.