Swimming provides a combination of an aerobic workout with strength building in your arms, core and legs. Since you’re in water, you are buoyant, which removes any shock to your joints. When you start a swimming program, you may find that it is difficult to complete a lap and you’re quite breathless, even if you are already fit. This is because swimming requires controlled breathing when your face is in the water, which takes time to learn. To progress as a swimmer, you need to take lessons.