Swimming

I've been advised by the health centre to try swimming for my arthritis issues. Having been a handful of times now though, I am barely able to move the next day. I appreciate it takes a while to get used to things, but has anybody else tried swimming and it's just not helped?

I was fortunate enough to find a private pool, so was able to go with nobody else there which was lovely, but whilst I'm happy to pay for the privilege if it helps, I just wonder if once a week is enough? I simply can't go daily because of work commitments and am feeling disappointed that having given it 'a fair crack of the whip', I don't feel any benefit from it at all...