Did 45 minutes

My wife and I went early to the South Jordan rec center. She swam while I ran and walked the track. I had planned to go an hour, but I aborted my workout after 45 minutes. All of a sudden, my left knee started to hurt. I used Arnica, Ruta, and Rhus Tox during the day, but my knee was still sore at bed time. It isn't quite as sore as it was this morning. I've been doing exercises to stretch various muscles, but I haven't been doing knee exercises, and I guess my knees had gotten weak. I hope it is just strain on my knee and not an injury. Time will tell.