With every year that passes, your body conspires to make getting into shape harder. Your metabolism slows down as you age, adding weight that you'll have a harder time shedding. Your growth hormone production slows down, making it even more of a challenge! What might have been a snap at 20 will take more time and effort at 45.
Here's the good news: You CAN absolutely get fit at ANY age! BUT....the longer you put it off, the harder it will be to make those changes.
Your body is more primed to respond to exercise right NOW, than it will be even 6 months from now. And, if you happen to be that 45 year old who starts working out today, know that soon enough you'll be fitter than a 20 year old who's sitting around still making excuses!