Old is a state of mind. Someone can be 80 or 90 years old and still be young. It really depends. You're only as old as you feel. Sometimes I feel like I'm 25.
Age is attitude.
Old is when you can't walk around anymore. I think 63 is old. My parents are in their mid-40s, and I don't count them as old yet. How someone carries themselves is what makes them seem old. Someone's old when they can't take care of themselves.