Halfway through his freshman year at college, Branndon Stewart lost the starting quarterback spot to a guy named Peyton Manning. But don't feel bad for him. Stewart, now 40, took the less injury-prone route to success. With hockey-stick growth, his Austin-based marketing automation service, OutboundEngine, landed at No. 95 on this year's Inc. 5000, a list of the fastest-growing private companies in America. Here's how the entrepreneur turned an upset on the football field into a key win. --As told to Melissa Studach

This was before the days of Twitter, and recruiting information wasn't quite as available. So Peyton and I both show up as freshman at the University of Tennessee to be quarterbacks. We were playing UCLA for the first game of the season, and our starting quarterback had a career-ending injury. The next thing you know, they're playing Peyton and me. The rest of that season, he and I played together, but Peyton was clearly going to be the starter, so I transferred to Texas A&M. We went to the Sugar Bowl, the Cotton Bowl, won the Big 12 South twice, the Big 12 championship. I had a pretty good career.

There's a long list of guys I played with that will be Hall of Famers. Being around so many athletes that operate at that level and understand the work ethic that's required to be successful starts to rub off on you.

After I finished my last game at A&M, I was ready to hang up the cleats and jump into the technology world. I moved to Austin and went to work for a startup, where I was thrown into the deep end of technology and how to sell new products to customers who'd never even heard your name before. That's how I cut my teeth.

From that point on, I worked for a few more startups in Austin. One was a promotional products company structured with a corporate entity and independent sales reps. On 100 percent commission, the reps were really running their own small business with some corporate support.

I realized their marketing strategy was waiting for the phone to ring. They didn't have the time and capacity to do it themselves, so I learned that the best marketing for sole proprietors was to automate those things for them. That was the genesis of OutboundEngine. In a little over three years, we've grown to almost 9,000 customers in basically every state.

It's tough to start a business, so having that experience of 100,000 people either cheering or booing at you is pretty good training for being able to take the ups and downs of launching a company. You learn really fast to have thick skin.

At the quarterback level, you have to operate with a lot of different personalities. If you sit down with a wide receiver, his personality and what he thinks about and cares about in the game are very different from those of an offensive tackle. There's some value in being able to build rapport across a lot of different people and get all of them to work together as a team, especially when there's a lot of stuff going on really fast.

Starting a company is like being thrown into the jungle and being told to get out and do a hell of a job of it. To do that and be successful is very rewarding, because you have to learn a lot on the way there. That's more rewarding than any sport achievement.