Gyms in the UK

So I have been looking for gyms in Edinburgh and Dublin, close to my hotel, so that I could pop in a couple times and work out on my vacation. I am having ZERO luck! The one closest to our hotel in Edinburgh said their daily rate was 70 euros! (Granted it was a spa as well) but could not find another gym within walking distance. The gym nearest our hotel in Dublin's daily rate was 25 euros! That is like 40 dollars... Am I doing something wrong? Surely there are affordable places to exercise? Any advice?