Elijah Arnold took down an alleged robber early Thursday morning at an IHOP restaurant in San Antonio.

"I just heard the register popping ...I stepped out and looked and there he was pulling the register out and everything so I just took off, my instinct kicked in and I took off full speed at him," the 22-year-old waiter said.

He said the man hit him in the face with a crow bar, but he was able to get him into a submission hold thanks to his training as a third-degree black belt in mixed martial arts.

"He tries to start apologizing and, 'Man I'm so sorry. I know I hit you. I know I'm trying to steal your money, but just give it to me. I need it really bad' and everything like that," Arnold said.

Arnold said in some ways he could relate. After working at IHOP for four years, he went down the wrong path and ended up homeless and addicted to drugs.

"That's kind of when everything went down the drain," he said.

Since then, he's cleaned up his life and IHOP gave him a second chance. He said that's another reason he was so quick to act.

"When I walked up to my managers today...they just congratulated me and said, 'Thank you,' and that was the biggest thing that I could have was the thank you from my managers," he said.