The problem with the idea of the midlife "crisis" is that it's more a period of change and not all crisis. And it's somewhat, but not all, about mortality. At that age, in your 40s, you've often had enough time to establish a career, and for many, realize it's not what you thought it would be. It has nothing to do with mortality; if you started your career earlier or later, you'd be reaching that point earlier or later. Also, you've reached a point of wisdom to realize, yes, exercise is good, maintaining your health is good, all these articles you've been reading about it for years are right, and so forth and so on. You might have a new family, which changes things at any age. And finally, speaking of kids, I do think there's something about the 40s being the new 20s, the 60s being the new 40s, and so forth. I could go on and on about many things that cause change, but don't have anything to do with death or even old age.
If you knew me, for example it would be clear that I am in fact in crisis in many ways, and have been in recent years, in the ways that the author suggests. But that's not what motivated me to do a triathlon. It has nothing to do with some need to prove myself or anything like that. It was all about being prodded by friends to join them, and it was something I had always been interested in. I've always been a little athletic. It could have happened in my 20s or 30s but didn't. Why my 40s? I'm not sure. I guess I've just reached a point where there are many things like triathlon I've been wanting to do for years, and am now getting around to it. When you reach that age there are things that accumulate like that.
I think midlife change is very real, and often comes as a crisis, but I think that focusing on the mortality issues that do arise is really missing many, if not most, of the other factors involved.
In the case of athleticism, it stigmatizes exercising and wellness. So you're doing a triathlon or a marathon in your 40s? Now this is a bad thing? Can those of us in our 40s get a break? It's another form of ageism in many regards.