I also highly recommend reading Morgan Housel's book, the Psychology of Money. If you want the short version, this is an MBA on investing mindset.
Honestly, I think it's the best 20 bucks you can spend, so just go to Amazon and buy The Psychology of Money. I am not receiving any payment for this. In fact, Morgan doesn't know that I'm recommending his book. But honestly, do yourself a favor, spend the 20 bucks, you'll be glad you did.