Swimming works the whole body so it is a great way to tone up and get trim. Swimming a few lengths involves most of the muscle groups and you'll get a good aerobic workout if you increase the pace. Swimming can also help you lose weight if you swim at a steady and continuous pace throughout your session. The ability to increase and decrease the intensity of this activity is great when recovering from heart valve disease treatment, because you control your workout.
Many swimming pools and sports centres now hold adult only/over 60s only/women only classes so you can be sure to enjoy your swim without the floats and bath toys! Use http://www.swimming.org/poolfinder to help locate a pool near you!