Meditation. Most days I meditate around the corner from work during lunch. It massively improves my mood, gives me new perspective, sometimes gives me a physical body high like a good edible, and helps me focus.

I usually meditate again before I leave work, which makes me less tired. I now have the energy to go out and socialise after work.

I initially dismissed meditation as stupid, but many of the smartest people I know and respect do it. Eventually I just said, "what if I'm wrong". Haven't looked back.

I can recommend starting with the Headspace app and The Mind Illuminated book.