To turn your hobby into a business you have to find a way to monetize it. If your hobby creates some kind of product, start selling it in some fashion. If you can teach others how to do your hobby, start selling your service in some way. If you can post your hobby online in some way, create a website, blog, or some other web based site and make money from advertising, selling directly to people, or in some other web based way. You can also start a business supplying all that is needed to do your hobby to others. Just find a way to get paid is some fashion and boom, your hobby is a business.
What do you think?