Go out for a walk every day, even in the rain. Helps during lockdown especially, I often walk 4-5 miles.
Don't drink alcohol, have never smoked. Take vitamin tablets with high B vitamin content, seem to help with mood.
Have cut down on coffee, don't eat meat every day, only have 2 meals a day...we don't need all the food we consume these days. I could do with cutting down on carbs but have found that harder during lockdown/winter. I do cook from scratch though and eat a lot of salad stuffs.
Did a digital detox some years ago, don't have Facebook, WhatsApp, Twitter, Instagram, LinkedIn.... Don't 'follow' anyone nor get 'liked' by no-one. Also got my name taken off dozens of lists, gave up all my store cards (the ones which harvest data) and so on...I personally think it's a much healthier way to live but others would disagree.
I walk rather than take the car wherever possible. Have lots of creative pursuits too.