Seriously, diversify your knowledge!
I'm talking: business, philosophy, history (especially history), gardening, cooking, YOU NAME IT.
The more questions you get answered, the more questions you have. Before you know it, you are smarter than yesterday.
Listen, I spend most of my days reading. I LOVE READING. I just read, and read, and read. I'm currently reading books about real estate, awesome recipes, and even wildlife.
Books feed your soul.
Whether paperback or ebook, start on some books today!