A New Hampshire man who lost his vision due to a neurological disease is not letting it stop him from completing some of the world’s toughest challenges.

Randy Pearce, who at 22 became blind and was forced to rely on a wheelchair, recently completed a Tough Mudder competition and is now setting his sights on running in the Boston Marathon, MyFoxBoston.com reported.

“I was frustrated and angry and all the reactions you’d expect because loss is hard,” he told the news station. “It’s like how much do you have to rebound from, how much do you have to climb up from? And the answer is however much is there to climb.”

Pearce first learned to walk again, and then mastered running. He’s climbed all the mountains in New Hampshire and completed three marathons within the past year.

“When you can’t walk, you learn what a gift it is to celebrate walking, climbing,” Pearce told MyFoxBoston.com.

A video of him swinging on a rope and ringing a bell at a Tough Mudder competition in California recently went viral.

“Don’t get me wrong, I have tough days and there are things that I try to do that frustrate me that are a lot harder because of my blindness,” Pearce told MyFoxBoston.com.

But Pearce– who loves turning obstacles into opportunity— hasn’t forgotten how quickly life can change and the importance of having a positive outlook.

“Henry Ford was probably right. Whether you think you can or think you can’t, you’re probably right, you have to start by believing,” he said.

Click for more from MyFoxBoston.com.