We usually use a private pool in a friend's home. No one else is ever in there when we are and we usually use a key code to enter. The police shut them down last lockdown even though no one was mixing and it was being cleaned each time and this time also they are not allowed to open. I agree that it's a bit dodgy at public leisure centres, but I also think exercise is beneficial for immunity and wellbeing.
Much as gardening is good for mental health, not everyone has a garden....and I think it will be bad for people's wellbeing to not be able to do the exercise that their bodies have become accustomed to do. There is some gardening I could do, but there isn't much that needs doing this time of year. I did write to my MP and signed a petition because I feel that people's mental health will suffer.
We are the lucky ones, with a dog that needs walking and a garden to potter in, but I really feel for those who don't.