You’re Most Likely to Do Something Extreme Right Before You Turn 30

Well, first off the title doesn't exactly match the content. Studies found that you're most likely to do something extreme when your age ends in "9" (29, 39,...).

Mostly, though, I was a bit disappointed that a marathon was considered extreme. I was thinking more like climb K2, sail around the world, that kind of thing. I've run plenty of marathons, they're hard (the training is really the hard part), but not what I'd call extreme. Hell, how many hundreds of thousands (millions?) of people run a marathon every year? The reason I call into question the definition of "extreme" is because a K2 climb or a big sailing trip cost "extreme" amounts of money, the kind of money I sure didn't have when I was 29.

Definitions aside, I think it would more accurate (and less click-baity) to say that people push harder to accomplish goals as they approach an age milestone. I'm not much of one for that personally, but even I've done it with the goal to run the Boston Marathon before I "got too old to do it". (It was mere coincidence that I was 50 when I finally crossed the line.) I think it's perfectly reasonable and not all that newsworthy when folks say, "I'd like to do $ACHIEVABLE_GOAL before I hit X9."

39 here, getting ready for something extreme.

Brb, I'm about to run an Ironman at 29.

It was true in my case when I turned 29. I founded a product and built a startup from that.