This past Sunday, Zac Vawter, 31, climbed 103 stories of Chicago’s Willis Tower with the first “thought-controlled bionic leg,” accomplishing a feat most of us couldn’t muster the strength to do with our natural legs.

Originally from Seattle, the Rehabilitation Institute of Chicago (RIC) research participant was accompanied by nearly 3,000 others in the world’s tallest indoor stair-climb event. Called “SkyRise Chicago,” it raised $1 million in research funds for the RIC. Vawter clocked in at an impressive 53 minutes and 9 seconds (which, coincidentally, is about 53 minutes and 9 seconds faster than I could dream of doing it in).

After losing his leg in a motorcycle accident, Vawter was fitted with his incredible bionic leg. As soon as he pushes on the device to stand-up, it miraculously reads his intent and pushes back on him so he can move upwards. Vawter, a software engineer, travels to Chicago to work with the team at the Center for Bionic Medicine to fine-tune his device.

Watch this video to learn more:

Learn more about the RIC here.