I swim in cold water, every day if possible and ideally before work in the morning. This has been a game changer in terms of reducing anxiety, being much better able to cope with difficulties and frankly, making me into a much happier and healthier version of myself. So much so that if I don't get in the cold water for a day or two then I just feel like .. bleurgh. If you've read "Flowers for Algernon" and recall towards the end where (spoiler alert) the main character has come off the drug that makes him much more intelligent and crucially - he can't remember what it was that had happened to him, just that he had a sense of loss from no longer having some <very very good> - that's what this is like. Can't recommend enough. I also use running for the same purpose, but cold water swimming in just a couple of minutes provides a tremendous dose of <good things.> Also it seems to stop me catching colds.