I'm an 18 year old athlete. I have played basketball, volleyball, and softball for aout 10 years now. While I'm at work, I am on my feet all day long barely getting any rest. My knees have become weak when I finally do get to sit, but I can't keep them bent or straight, I constantly have to keep them moving in order to not feel much pain. My feet are hurting as well, what can I do to put my knees at some sort of comfort?