My Christmas party last year saw all my students running around and being their energetic selves.  Most were in the 5 - 8 year old bracket.  At one point they decided (mob rule - Isaac Asimov knew something) to attack sensei.  They made the rules...  Get Sensei!! They Tag-Teamed without knowing how, when one slowed to catch his breath, another stood up to take the challenge. I ran, I blocked and countered.  Flipped, dropped and twisted them.  Pushed, covered and defended.  Attacked, grappled and moved. It took about half an hour but they eventually ran me down...   I felt old. They had shown me something I wish I could have taught them. Think of Bruce Lees teachings. They didn't know they could lose, I knew I'd have to stop at some point. We learn lessons from the most unlikely places.