When I was a teenager growing up in Poland I started having problems with my knees. They were painful, I could not stay in the same position for a long time. Even driving a car became a problem. I've heard that smacking your knees with stinging nettles could help. So I did it. Yes, it was a little painful but I did it any time I was able to get ahold of wild nettles. Each time my knees got hot and red. Low and behold, my knee problems were gone to never come back:))