Your breast size is determined by your genetics and your percentage of body fat. A well-rounded exercise program includes strength-training exercises along with aerobic exercise. If you are worried about getting bulky muscles and want to simply tone your muscle tissue while also getting smaller breasts, avoid lifting heavy weights and focus on fat burning exercises.
Perform lightweight and high repetition training when you lift weights. This form of training improves your muscle tone and endurance without increasing muscle size. Use hand weights and perform exercises like the bench press and flyes that you can complete 12 to 15 repetitions with easily. The last two or three repetitions should feel more challenging but not impossible.
Work out in the morning before eating breakfast. According to Gretchen Reynolds, health writer for "The New York Times," working out before breakfast leads to more weight loss. Eat within an hour of your workout to refuel your body.
Perform aerobic exercise after lifting weights. It takes at least 15 minutes for your body to start burning body fat. This can lead to more weight loss and decreasing your breast size quicker.
Perform at least 30 minutes of steady-paced aerobic exercise five to seven times a week. Choose an aerobic exercise, such as running or the elliptical trainer, and work at a moderately fast pace for the entire duration of the workout.
Complete aerobic interval training on the days you do not complete steady paced aerobic exercise. Interval training burns more calories than moderately paced activity, but is too physically demanding to perform more than three times a week. Alternate between a very fast paced interval of the aerobic exercise you choose and a resting pace for up to 25 minutes. Perform the fast intervals for 30 to 60 seconds. The resting interval should be twice as long as the fast interval.