Wow! If you think 45 is pretty young, if you live to 90 you would be middle aged.
Don`t worry, though, if you Don`t grow by age 50 you Don`t have to. The only drawback is you can`t retire until 3 days after you're dead. That's why at 72 I`m still working. Gotta pay for my transgressions when I was young.