Swimming

This focus on timing when to breathe also gives swimming a yoga-like quality: all you’re thinking about in the water is getting a good lungful while all you can hear is air bubbles passing by your ears. It’s very peaceful and, as you’re not aware of anything else happening around you, your mind tends to empty itself of life’s stresses and strains. So, coming out of the water, even after a long swim, you feel a good deal more relaxed than when you went in.
https://www.irishtimes.com/life-and-style/get-swimming/fitness-50-lengths-a-lunchbreak-secrets-of-a-regular-swimmer-1.2108398