Seven years ago, professional rock climber Lai Chi-wai lost the use of his legs in a car accident. But that didn’t stop him from continuing on with the sport he loved. Lai was recently honored for climbing Hong Kong’s Lion Rock, a mountain taller than New York’s Empire State Building.

Lai pulled himself and his wheelchair up the rock face using a series of pulleys. These simple machines are made up of a wheel with a groove to guide a rope. They make it easier to lift heavy loads.

“Climbing in a wheelchair requires incredible upper body strength,” says Zach Brinchi, the outreach coordinator for USA Climbing, which oversees competitive climbing in the U.S. “It’s essentially like doing hundreds of pull-ups over and over again.”