Most self-made billionaires do these things daily:
Read books not directly connected to their work or profession. It gives them a totally different perspective on their work and life. Reading biographies is an excellent way to learn form the lives of people we may never have met.
Get out of your comfort zone. The idea is to get comfortable with the feeling of incompetence you are bound to feel when doing or learning something new.
Exercise regularly if not daily. The benefits of regular exercise cannot be understated. A regular exercise regime can do wonders to your body and mind.
Give back to humanity, be it in the form of money, time or any other resource at your disposal. Andrew Carnegie, Warren Buffet, Bill Gates… the list is endless.
Get out to Think. The outdoors, a quiet walk in the park, maybe the best way to clear your thoughts. Give your subconscious time to process your thoughts and present you with a solution.