T-Cross Sit-Up You'll feel that amazing burn, even if you didn't make it to the gym. Begin lying on the floor with your legs straight and arms out wide to the sides, making a T with your body. In a slow and controlled motion, sit up, lifting your right leg and twisting to the right to bring your left hand to your right toes. Hold this position for a moment, pulling your abs toward your spine. Slowly roll down to return to the starting position to complete one rep. Repeat on the other side. Perform 15 reps. Image Source: POPSUGAR Photography / Kathryna Hancock