How do I get started in business with nothing?

I don't come from a business background. I started studying stocks and investments a couple year ago because the opportunities available are amazing. The potential behind exponential growth keeps me up at night sometimes. Recently I realized that the same exponential growth is possible in business with continual reinvestment of profits, which excites me greatly. However, the more I look into creating my own business, the more the probable expenses add up. Is it possible to start from nothing and work your way up? Or does it always cost so much just to get started?