I'm not sure how a motorcycle accident relates to age. I know a woman who had a m/c accident at about age 30 and has been paralyzed from the neck down since. I think the question is more about how are you doing at your age vs. how you thought you would be doing.
I actually remember being about 10 and talking with my friends about how cool it would be to see the changing of centuries at the 2000 new year. We did the math and realized we'd be around 40+ and since our parents were around that age, we figured we had a good chance of making it. As I got older, I was a bit obsessed with diet and excercise and felt I was invincable. I assumed I'd live to be an active 100 y.o. I was never sick and never in the hospital except some stiches in the ER from a sports mishap. I played very competitive sports until about 50 when arthritis forced me to stop. Now in my 60's I have declined quite a bit in the past 10 years. Hip replaced, cancerous prostate removed, a bout of pancreatitis, etc. A woman about 10 years younger than me just had a heart attack and is in intensive care and may not make it.
So what's my point? Aging sucks and you can't predict or prevent what may happen, you just have to deal with it when it does. Do your best to make good choices in life, but that by no way guarentees a good outcome, just increases your chances a little. My mom, now in her late 80's says that 70's are not that old, but 80's are. I wonder if she will say the same thing if she reaches 90. We tend to think in terms of decades which I think is a fair barometer of the "steps" we go through in old age.