Is breast enlargement by exercise safe? The only side-effects could be an increase in your overall fitness, which obviously can’t be bad. Just don’t concentrate on your breasts to the extent that you neglect your back, and don’t overdo the exercising. Are exercises effective for enhancing the breasts? Exercise is good for breast enhancement as it tones the breasts and prevents sagging. The actual size of the breasts cannot be enlarged by exercise alone, but they do become more shapely, perky and sexy. It is interesting to note that the very effective Breast Actives system for natural breast enhancement combines herbal pills with a cream and a special program of breast exercises.