In reply to Wiley Coyote:
I'm 34, and already have a fair collection of injuries of my own. I wouldn't take kindly to being told to give up chasing my goals, and I don't see why you should.
Being sedentary doesn't just bring a risk of heart disease, it also comes with a range of joint problems, back pain, 'gammy legs' and all sorts of stuff that not only costs the taxpayer money, but also reduces that person's ability to contribute to their own families and communities. I'm not saying that a bad back makes someone socially useless, but that the handiness of a 'granddad' who can take the kids out for a walk or help put up a set of shelves is pretty significant. And staying active needs you to be motivated and passionate - if you're not that bothered about a day of easy classics then soon enough you'll stop doing it.
I'm sure also that remaining active and engaged with one's passions (and staying ambitious and driven about it) must help to maintain mental health. I bet there's a correlation between people who keep up their hobbies at the highest level into retirement and those who remain positive figures in their families and keep active in professional and voluntary roles.
Most importantly, though, there is an incalculable social benefit from people doing the thing they love with intensity and commitment. The people I look to for wisdom, advice and mentoring are those who have the benefit of a long life well lived, but who have continued to engage with the world in a way that is positive, intense and heartfelt. Folks in their 70s and 80s could justifiably become either cynical or out of touch, but those who continue to meet new people and do the things that enthuse them will tend to be realistic and encouraging sources of advice. For some people, it might mean hoovering up novels and attending literary festivals. For others it's woodwork. For some its sport climbing, fell-running or audax. I've met so many people like this, and seen the charisma and insight that they offer to others, that I think the world is richer in every sense for their presence.
I'm not sure you can measure the economic benefit of all of that, though if you ever could I bet it would be substantial. In any case, the value in making the world a more fun, varied and interesting place is inestimable. So if you're 'getting on' (and only you can be the judge), then do what you like. If that means climbing until you start falling to bits, then I think you've given something to society rather than taken it away.