Psychology of Money by Morgan Housel is one book that has had a profound influence on me in regard to how we think about money. It's not exactly related to trading but I think everyone should read it as it has great insights on how we think about money, success and happiness with real life examples.

Other than Trading in the Zone by Mark Douglas is another book I will highly recommend to anyone who aspire to be a trader or even if you already are a seasoned trader.