Psychology tests show that announcing your goals makes you less motivated to accomplish them.
For the TED Conference, you can submit a few different ideas for a talk you'd like to do. For this TED, I submitted three ideas. Two I was excited about, and one as an afterthought. Of course they chose the afterthought: this talk.
I'm really no expert in this subject. I had just read an interesting article in Newsweek Magazine about this, then did a little sleuthing to find the original research, then presented what I'd found. Total time spent: maybe 5 hours. See the original article, full of links to more information, here.
Since people on the TED stage are usually experts, people have taken this talk far too seriously. It was really meant as just a 2-minute eyebrow-raiser. A little something to think about. That's all. But over 400 comments arguing about it on the TED page for it.
But I wish I would have included one important point, that makes a lot of difference:
These studies are only about identity goals: goals usually related to personal development, that would make you a slightly different person if completed.
This does NOT apply to things like starting a company, brainstorming, or other pursuits where it would be useful to corral a bunch of people to support your project.