In my case it's the occasional foray into soldering electronic kits as I was wont to in my youth.
Not for any real end other that keeping my soldering skills up to snuff, even if the old hands shake more than they ought to, and not letting my modest skills atrophy, as well as the mind cleanse you refer to, especially now that life's autumn has started to turn to winter.

It's my modest way of showing there's life in this old lad yet! (snort.)