Abs - Heidi Klum got her six-pack stomach by working her abs HARD! She used a stability ball exercise that’s sure to tighten and tone! Lying face up, hold a stability ball with your hands extended over your head. Raise your arms and legs at the same time, meeting halfway over your abs. Tranfer the ball to your ankles and lower your arms and legs back down to the ground. Repeat and prepare to see results!