Awesome!
Just turned 50 last spring and have been riding fixed for sixteen years. Three years ago after riding conversions I finally got a frame that's actually designed to be a ss/fg with track ends. Much more enjoyable than a conversion. I have knee problems too and I've found out that riding fixed actually helps my knees. Also at my age I can set up my bike how I want it and I don't have to follow trends or worry about "street cred" or being a hipster or whatever and I'm too old to do skid stops, trackstands and alleycat scrambles.