A lot of people say too much gaming is a bad thing and while I think it depends on who you are talking about, I agree. Sitting too long is not good for your health in general. I'd have to say anything beyond 2 hours is too much. If you are sitting still playing a game for 2 hours, you should take a break from it and move around for at least an hour or two.
But I do agree though but then again, if I work in the office and sitting long period of hours - that means I am putting a lot of strain on both body and eyes.
Either or, not very good, I need a new career.