My shoulders are sore and somehow my feet are protesting a little too. I went swimming for fourty five minutes yesterday. It must have looked like a fowl was drowning. All arms and legs thrashing helplessly. But that was just the first couple of laps.
After that it got better. I remembered to breathe and I tried to concentrate on technique. Not that I have a very good technique, but by doing so I got into a rhythm and that helped. With a decent rhythm I relaxed and I decided that that was the key to swimming. If you want to swim for a longer period of time, you need a good rhythm. A bit like most things, really.