If I was a kid . . . or, you know, in shape . . . maybe I’d have this much energy.  Maybe . . .

A 10-year-old kid in San Francisco named Niall McDermott just finished a pretty impressive feat this past Sunday.

His grandfather has been battling lung cancer, and he wanted to do something to support him.

So Niall challenged himself to run FIFTY 5K races in fifty days.  (For those of us who hate the metric system . . . and/or running . . . 5 kilometers is just over 3 miles.)

His parents talked to his doctor about it first, and told Niall he could stop whenever he wanted to.  They figured he’d quit at some point, and didn’t think he’d actually do all 50 races.  But he did.

He ran his first 5K at the end of August . . . ran his 50th in San Francisco on Sunday . . . and raised about FOUR GRAND for cancer research in the process.

He says he got the idea after he saw a documentary called Iron Cowboy, about a guy who did 50 Ironman races in 50 days.  (KPIX)