Then when?!

The biggest reason that I use to try to force myself to get into shape is to tell myself "if you wont have the body or the fitness you want NOW at your age, then when will you?!". If in my mid-20s, and I am saying that to scare myself of my age even more, I cant find enough of a reason to look and feel good then will I when I am 30, 40, 50? At that age, I'd be able to use my age as an excuse NOT to be fit! I need to get my butt off the damn pc that I sit on practically all day, whether at work or at home, and do something! I want to be able to look at myself in my 20s and feel that I was in the best physical shape that I could have be in at that age. GET UP AND DO IT!