Before he passed away in a tragic car accident at the age of 21, Ryan Sims wrote a letter to his younger brother, Tony. The main thing he wanted to get across read “you’re wasting your talent, you should continue to compete.”

Davenport, Iowa’s Sims brothers were always doing whatever they could to stay busy, as long as it involved a winner or loser at the end of it.

“We grew up fighting,” Tony said. “That was what we did. We were boxers since I was seven years old.”

The younger Sims eventually earned seven Iowa state titles in the ring, but once he began studying at Iowa State University, his focus was on academics and his future career as an engineer. Ryan, who had just finished up basic training in the Army when he died, had other goals for his brother, and they all had to do with getting back to combat sports.

“He (Ryan) challenged me to do this tournament, and that’s what started this whole thing for me. A couple months after he passed, I was back at it.”

Ten years later, he is a member of the UFC roster, called into action on short notice to move up from lightweight to welterweight to face The Ultimate Fighter 21’s Steve Montgomery.

“It was very important that I get here,” Sims said.

Owner of 11-2 pro MMA record, the 29-year-old now makes his home in Denver, where he trains with the likes of Leister Bowling, Christian Allen and Eliot Marshall. He graduated Cum Laude from Iowa State with degrees in Architecture and Engineering, and he currently works with another pretty fair fighter with a day job in the engineering field, former interim UFC heavyweight champion Shane Carwin.

“It’s unique and it’s a small world for engineers in Colorado right now,” Sims said, and when asked if the company he and Carwin work for is the toughest engineering firm around, he laughs.

“You can definitely say that.”

But just like Carwin likely heard a hundred people wondering why he would compete as a professional fighter with an engineering career as his day job, Sims heard (and hears) the same thing.

“I get those talks to this day,” he said. “You know fighters, it’s hard to explain (why we do this). I definitely don’t do it for the money. I have a career outside of this, but this is about passion, about what I love to do, and I don’t think that I can quit doing it anytime soon.”

Given his success thus far, there’s really no reason to walk away, especially when things are really just taking off. Winner of three straight, with his only loss since 2088 coming via split decision to UFC vet Drew Dober in 2013, Sims knows that he’s ready for the step up to the big show. In fact, he knew it a couple years ago when he returned from a three-year layoff to run off a 6-1 record.

“It (the layoff) wasn’t because I wanted a break,” Sims said. “I had a lot of injuries and I started working as an engineer, so I had to make sure I spent time on that, and then I came back to fighting when I was able to do so. But I was always training and I was always working for that goal (of getting to the UFC). I remember training with some of the best guys around and doing really well. I knew in my heart that I could be at the highest level, and I talked to my coaches and said ‘let’s get back to fighting.’”

He hasn’t second-guessed himself since. This is where he belongs, and before he even knew it, his brother Ryan did. And now that he’s kept his promise, Tony Sims looks forward to what the future holds.

“As a competitor, we have to set immediate goals and we have to set long-term goals,” he said. “I think getting into the UFC is more of an immediate goal. Long-term, there are approximately 500 people on the roster. I don’t consider myself one of the top 500; I consider myself a potential top ten fighter at 155 pounds and I think that people will learn that soon.”