I learnt to play the piano at the age of 5 and one of the first things they teach is how to hold your hands and wrists.
So far I have never had any problems with repetitive strain injury when using a computer keyboard and I put that down to using the same technique on the computer keyboard to the one I use on the piano keyboard.
If you start to get joint pains relating to computer keyboards and it isn't posture related cut down on the tea/coffee intake. Try taking glucosamine supplements. They do take an affect.
For 10 years I used to cycle to work whenever the weather permitted. I found that my stress levels were far lower while I was doing this even though my job at the time was far more stressful than it is today.
I would seriously recommend taking up some for of excercise to combat stress, even if it is just walking. Don't go to one of those overpriced testosterone filled gyms, they are not stress free! The oestragen filled ones are even worse, particularly when trying to cope with a mid-life crisis