I had a very similar reaction. I rode a century (100mi) bike ride this spring, and telling people I was doing it was an important part of staying motivated. Also, because the ride was a charity fundraiser, once I had people sponsoring me (i.e. donated money to the cause) I felt like I couldn't back out.
I think the difference between this sort of goal and what's described in the article is that with a lot of intellectual pursuits, just telling people that you've been thinking about it and sketching out how you would do it gets you 80% of the respect and satisfaction for 20% (or less) of the total effort. On the other hand, you don't get much cred for just saying you're going to do a marathon or tri or century.
I think the difference between this sort of goal and what's described in the article is that with a lot of intellectual pursuits, just telling people that you've been thinking about it and sketching out how you would do it gets you 80% of the respect and satisfaction for 20% (or less) of the total effort. On the other hand, you don't get much cred for just saying you're going to do a marathon or tri or century.