Even thou I liked that funny porn things, I would like to give a serious answer to this issue, as it occurred also to me and got pretty bad.
I always dreamed to learn to play guitar but until RS my life always pulled me away from it. (you'll see why I say this).
Than, at the age of 34 I started to invest more time in guitar as music became as a soul saver for me (on some other personal issues). So I just found myself many times trying to play and at a moment I just started to feel pain in my hand and I was even unable to move my fingers properly when I stopped playing.
I could not accept the idea of taking a break, so when the pain became more and more present I had to go to see a doctor. The remedy? One month of hand rest and we'll see....The moment I stepped out of his office I was thinking only to go and play, so I went to see someone else, to get a second opinion. There, I got some massages and something as an order: "you started playing at 34, your body is not so young anymore you cannot rush it into things. You need to train your muscles and you need to do that gradually. Pay attention to your body needs and he will be your friend. Otherwise you'll just end up quitting." Three months ago, my hand was swollen at the wrist. So I started to exercises...some from RS (already mentioned by Attitude) and some I did for myself to repeat things that I was unable to play comfortably in songs. Now, my hand is normal, the pain went away, there is not one day when I'm not playing and sometimes when I have time I just find myself playing for hours and my mind and concentration loses focus before my hand.
So, I just laid out a story, a real event which I have experienced, but the idea is this: warm up, exercise and build your own exercises focusing on what you cannot play properly. Do it alone, to be able to allow your body to set the pace, but no matter how slow you go do it correctly and in time you'll just see that in songs your hand will respond naturally.