Hey there Kcho, the best thing I found was meditation. Which is hypocritical of me, cause I stopped doing it several years ago. But for two years I had a practice of 20mins meditation twice per day and it really helped with a lot of things, calmer mind, less racing thoughts and better focus......over all feeling of well being. Why did I stop

beats me.
You hardest thing for me was finding a meditation practice I could connect with, there are so many. The one I found was a mantra meditation where you simply repeat a word in you head over and over, as you continue to do this, your breathing slows down, thoughts become less frequent and a feeling of calm. But it's not just during the times of meditation, it carries on throughout your day, you don't get upset as easy, your super relaxed. Again....why did I stop...stupid.......I need to start again. He funny thing was, the book I got was on kindle and really cheap, but the author explained it so easily and it was so simple. If your interested I can send you the name o the book.
Brian