Yoga. It's the only time in the day where my brain is not in overdrive. Also, as a 36-year old with a sedentary lifestyle it's surprising/horrifying how stiff I've become. I'm just following the beginner movies on youtube and I go to the occasional class, so it's not stressful.
I do a laughable 30-45min but I do it every day.
It's funny how formerly painful things like squatting, leaning etc. have become so much easier now.