Yes, this is exactly what I'm doing (swim coach) and happy with it so far. Feet for me, knees have been holding up after decades of running.You bet. I "hit the gym"--hired a swim coach for a few sessions. Before Fundies, I could manage to swim, but I had never properly learned to swim laps, and my lack of technique made it inefficient and exhausting. The swim coaching was worth it. For several years now, I have added swimming laps to my regular exercise routines. As the old knees complain about the decades of running, I've started to shift more to swimming.