If you love gaming, start looking after your fingers, wrists, neck and back etc right now. When you're old, you might not be able to go outside and as much, but being able to play games, and exist online, could be the difference between a sad existence and a happy one. My biggest fear is not being able to use a PC due to health issues like arthritis and others.
I once played Everquest when I was like 12 years old and grouped with an 80 odd year old. He mentioned that he was lucky that he 1) new about video gaming and it's potential for non-physical recreation and social interaction and 2) didn't have arthritis or anything that prevented him from using a keyboard/mouse. Other people his age were just sitting in front of a TV all day.