The procedure takes about 3 hours, and the effects last up to six months. It is recommended that you wait at least 6 weeks before doing any strenuous physical activity. Breast enhancement is a surgical procedure that can be done with either silicone or saline implants. The procedure takes about three hours and is done under general anesthesia. The implants are placed under the pectoralis muscle and take about six months to fully settle into the breast tissue.