"Execute a chest workout to target the pectoral muscles. The pecs run underneath the breasts. Building these muscles up will help keep your breasts lifted as you lose weight. Target the entire chest with exercises like incline presses, flat bench presses, decline presses and flys. Aim for eight to 12 reps, do four or five sets and use the heaviest weights you can handle. Have a spotter on hand for assistance if need be. Train three days a week on noncardio days."