Breasts are made of milk-producing glands, tissues and fat---not muscles. Unlike with muscles, breasts cannot be easily toned or shaped. The best way to get the breasts you want is to accept the breasts you have. Of course, this is easier said than done, especially in a society that values unnaturally large, lifted breasts. Sagging breasts are a normal part of aging and are common after pregnancy and breastfeeding. While you can't directly tighten loose skin on sagging breasts, you can tone the muscles surrounding your breasts to give the appearance of a firmer bust and get rid of excess loose skin.
Get a professional bra fitting to find the right size bra for you and wear bras only of this size. Besides taking a load off your back, a properly fitted bra will keep your breasts from sagging further. An ill-fitted bra leaves your breasts at the mercy of gravity and excessive movement, both of which cause breasts to sag.
Develop a strength training routine to tighten the skin in your surrounding chest muscles. Strong chest muscles are like a natural push-up bra; plus, they help tighten sagging skin. Get some weights and do sets of dumbbell chest presses, dumbbell raises, chest flys and dumbbell side lateral raises. Also do push-ups and isometric contractions. Meet with a personal trainer to learn the correct way to lift weights and develop a plan to target your chest muscles.
Do yoga and pilates. There are many positions and exercises, such as the headstand and inverted leg stretch in yoga, that work to strengthen the chest area and fight the effects of gravity.
Moisturize your skin with a skin-firming lotion. There are many lotions on the market claiming to reduce fat and get rid of excess skin, but only a handful of these creams actually work. Read consumer reviews of different brands to choose the right one for you. Massage the cream over your chest area as directed.
Get corrective surgery to fully rid yourself of that stubborn sagging skin. A breast lift tightens skin around the chest area and removes sagging tissue while working to lift and define breasts. A breast lift with implants restores fullness via silicone implants. Of course, surgery should be a last resort and only be pursued when all other procedures fail and you absolutely want to rid yourself of any sagginess.