The slim small waists many of us desire don't come for free. It comes from focusing on training the oblique muscles located on the sides of your stomach. Toning these will act almost like a belt and tighten all of your stomach muscles. 1. Get on the floor and lay down flat on one side. 2. Bring the top leg forward the opposite side of the body. 3. Without moving your lower body, lift your upper body as if you're doing a crunch. 4. Keep your core tight throughout this move and exhale on your way up.