I'm an avid football fan. I even attended a Super Bowl, years ago. There's an expression, NFL stands for "not for long." The average NFL career lasts about four years. How long does a career last for the regular guy? Perhaps you began your work right out of college. That means about forty, forty-five years. That's if things go according to plan. Layoffs, changes, life changes happen. Maybe your job becomes obsolete. Maybe you don't have a real career, and just work at a series of jobs, a few years at each.