13-year-old Nathan Boyer was at baseball practice outside Phoenix, Arizona last month when his coach collapsed.

Isaac Wenrich is the coach and it turned out he was having a massive heart attack. Which is crazy, because he's only 26 and in good shape. As of last year, he was still trying to make it as a professional baseball player.

Nathan thought it was a joke at first. But when he asked Isaac if he was okay, he didn't get an answer. He flipped him over onto his back, grabbed Isaac's phone, and used it to call 911.

Nathan started doing CPR, which he says he learned in the Boy Scouts a few years ago. Even though he hadn't done it since then, he ended up saving Isaac's life. Firefighters got him to the hospital, and his doctors think he'll make a full recovery.

Read more at ABC 15.