The story of a CrossFit enthusiast who was back in the gym lifting weights three weeks after losing her arm in a car accident has inspired thousands.

Krystal Cantu lost her arm above the elbow in August last year, but she can now lift more with one arm than she used to be able to with two.

Now Instagram videos of the Texas 25-year-old lifting barbells above her head one-handed are teaching thousands a valuable lesson about adversity.

"The accident was the best thing that could have happened to me, so much good has come out of it," she told Barcroft TV.

"I've inspired so many which I still find really odd and strange."

But since then she has become even more involved with her love of CrossFit, and now wants to pursue it professionally.

"I feel like I can conquer anything when I'm in the gym," she said.

"I feel like I have super powers when I'm in there."

Her story has gained worldwide attention in recent days, and fans have come forward to express their astonishment and their appreciation.

"I thank you for the motivation you give me when I'm at the gym," Facebook user Michael Lopez wrote.

"When I have that thought of giving up I think if you and if you can then I can!"

Cantu was the passenger in her boyfriend's car when a tyre blew and it flipped, severely injuring her arm.