I live by this factor. I have always had an energetic perception of the world and used my body to vigorously pursue many of the engaging activities this life offers. I'm not a fitness freak, but I've always tracked to the upper percentages of activity relative to my age. And I suppose most of the folks on this forum are this way too. The other day I was thinking about how healthy I am and then I laughed because I am: 66, Type 1 diabetic (since age 57, go figure), arthritis in hands that flares up periodically, lose of cartilage in wrists making shooting a ******* stronger than a .22 painful, Wear two hearing aids (lifelong nerve deafness that just progressed as I got older), wear trifocals, missing as many teeth as I have left...but none of that matters. I work as the senior copywriter in a young company and I'm always coming up with fresh and original ideas. I can easily ride 50 miles on my road bike, or climb the hills around the city on my 44 x16 single speed and commute to work daily. I climb mountains on a mountain bike and love the steep approaches, because you elevate your view faster. And I do all this, not to get into shape or "be healthy" but because I am passionate about investing my spirit into this life. I would only add that working the "creative" muscle is well advised in senior years, but don't wait that long to start. All material things pass, but art last longer.