Runners are gearing up for Sunday's half and full marathon downtown, and if you're a fan of the Rockets, don't be surprised if you see Clutch the mascot running the streets and running with a purpose.

For the past 19 years Clutch has entertained hundreds of thousands of Rockets fans of all ages.

Now the man underneath the costume, Robert Boudwin, is taking Clutch to the Houston Aramco Half Marathon Sunday morning.

Boudwin will run 13.1 miles in costume, all in the name of the charity Donate Life Texas.

Boudwin is running to help build support for organ donation/ He says he'll have a support group running alongside him.