As a woman gets older, the amount of glandular tissue diminishes which results in saggier breasts. The skin is no longer elastic enough to adapt to the reduced amount of tissue inside, making the breasts hang downwards. But It’s not just age that makes breasts sag: fluctuations in weight and pregnancies also take their toll. Unfortunately, exercise has no effect on the firmness of the breasts, because they don’t contain muscle. Only the large pectoral muscle under the breasts can be toned through activities such as swimming, rowing and yoga, but the breast tissue itself will remain just as slack. Only by enabling the glandular tissue to grow (again) - or enabling the skin to tighten - will breasts become firmer. You can read more about this in the Breast Enlargement and Breast Firming sections.