Football season started..

Today I played football with 6-9 years old kids, me and one other teacher participated. I was surprised how good they were! When my team was losing I needed to start play properly.. after all my team won and I made one goal :D while playing I felt little pain at my calf and ankle. But it didn´t started to ache bad, until I drove back to home by car. When I got home it was difficult to stand on it. Needed some painkillers to be able to stand and do some vocal recordings for ambercrape. What´s the lesson.. I´m getting old and I should not play so much with youngsters and act like one...