Things don't have to change quickly at 70 but that is around the time when you either start collecting the interest on your investments (or lack thereof) in healthy living and psychological/emotional growth, or the costs of not investing.

Health and vitality can still be restored to some degree, though it takes longer every year...start now! When my dad was in his middle 70s and I was in my middle 40s and a full time carpenter, I couldn't keep up with him in the weight room. I plan to use his example of what is possible as motivation;)