Lessons in optimism from very ill children inspire pediatric oncologist Jim Olson in his hunt for better treatments for brain tumors.

He’s a cancer researcher, physician, cyclist, kayaker and cook, not always in that order. He approaches each activity with incredible passion.

But to really understand Olson, you have to watch him in action with patients.

My remarkable visit with him, a part of my series, “Joe’s Big Idea,” begins on the top floor of Seattle Children’s Hospital. It’s a Wednesday, pediatric tumor clinic day, and Olson is zipping down the hall while I try to keep up. We enter a small, windowless room where the pediatric cancer team gathers before seeing patients.