I am not a work-out fiend, but I do moderate exercise.
My wife, however, at 53, has the exact same body she had in college - Yay for me!! - but she gets it by a dedicated workout and eating schedule. If she doesn't, she gets grumpy and agitated. I'd say yes she NEEDS her exercise, it's like a drug to her, endorphins and all.
But in the end, why worry? It's good for you. Do you feel the need to be able to exist and feel "normal" without working out? Or is your case one of those where it's excessive, you're spending multiple daily hours doing it, such that it interferes with your lifestyle, friends, family?