I was watching a good mental health special the other week - I think it was Trust Me I'm a Doctor - where they were talking about the benefits of exercise on well-being. What was a bit different was that it talked about some types of exercise being more beneficial than others. All forms of exercise are good, but where something like walking can give you a lot of time for rumination - something that's ruined many a walk for me - an exercise like rock-climbing requires concentration and mind-body coordination. This makes sense as you are very much in the moment. Not everyone can rock-climb of course, but I like cycling and have noticed that I forget everything else as it needs my full attention.