I am very glad to see that RSI (Repetitive Strain Injury) is the subject of a talk at PyCon Ireland.
The world is full of programmers in the 20-30 year old range, regularly pulling 18 hour coding sessions without giving it a second thought. Only taking breaks for restroom use, eating at their desks...
You can do that in your twenties and thirties but chances are, when you get into your forties, your hands and arms are going to start complaining.
As the saying goes, "I was that soldier". But, at least in my case I was mostly working with desktop machines and large-ish keyboards in my crazy coder days.
Compare today's high-octane coders. Weapon of choice is a laptop, often rested on the knees or propped precariously on a table along with 12 other laptops, hunched shoulders, knotted brows, bad light...
Not good. It *will* catch up with you. Speaking from personal experience, there is nothing more depressing that wanting to code and not being able to because you hands/arms are screaming at you. At one stage, I was reduced to tapping keys with the eraser tip of a pencil in order to get my e-mail.
Don't do what I did. Pay attention to RSI risks in your twenties/thirties and with luck you will never be visited with any problems.