Ronnie Coleman, 51, an eight-time Mr. Olympia, retired his belt and started a nutritional supplements company in Boynton Beach, Florida.

--As told to Zoë Henry

As my athletic career was coming to an end, in 2007, I asked myself: Do I want to work for somebody, or go out and make a difference? I learned the ins and outs of the supplements business as a bodybuilder. I'd worked with some of the companies, and I knew a lot about the products. Some of them worked OK, and some of them didn't. I wanted all of them to work, not just for me, but for other people, too.

Where I'm from, Bastrop, Louisiana, you played football, basketball, and baseball, you ran track--and that was about it. When I graduated from college, I tried my hardest to get a job at an accounting firm, and it just wasn't meant to be. I ended up delivering pizzas and newspapers. I knew my life was cracked up to be a little more. That's when I joined the police force in Arlington, Texas, and got seriously into fitness. I turned pro within two years.

I know what it takes to be a great bodybuilder. You have to get a lot of sleep--you actually grow muscle when you sleep--and you have to work out a lot. Most of the time, supplement companies sell products that give you way too much short-term energy. They cut corners by not adding different types of ingredients. So you get this real high, and then, all of a sudden, you crash.

I wanted a formula with sustained energy that would build muscle. Signature Series Myo-Blitz uses 18 ingredients to help you stay energized while building strength. It gives you a medium type of high, so you won't crash while you're working out. It costs a little more to manufacture, but it's worth it to see people building muscle. Other products can also help you lose weight, and get smaller, depending on what your goals are. One of our first products, Resurrect-P.M., is designed to work while you sleep.

When I started the business in 2011, we had no money. We've never had investors. My co-founder, Brendan Ahern, and I had already established relationships through working in the supplements industry, and we pitched our dream to them. The capital came from the pre­orders we sold to those distributors, like Prometheus, our main European partner.

I'm the marketing guy because of what I've done in bodybuilding. So I'm on the road about 300 days a year. I was just in Australia for two weeks, going to different stores, signing autographs, and answering questions about our supplements. I went to India. I also hung out with the president of Bulgaria, where bodybuilding is really popular.

We're trying to reach everyday people. We changed our logo to look softer and more appealing. Right now we sell in more than 120 countries through about 35 distributors. And when it comes to the R&D portion of it, we're really strict. We have consultants in various countries looking at the ingredients we use so that our products are legal everywhere.

I never wanted to be the kind of person who sits around and takes orders from somebody. I'm the kind of person who inspires people, and goes on to bigger and better things. That's the person I believe I was put here to be.