What I think about TED "Keep your goals to yourself"

I would like to write about a talk of TED "Keep your goals to yourself" by Derek Sivers.

http://www.ted.com/talks/derek_sivers_keep_your_goals_to_yourself

In my youth, I was the type who practiced my goals after sharing them.  But now, as for my personal goals in life, I don't state them clearly/publicly.  There are a few reasons for this.  First, I'm not sure how to achieve my goals.  I don't think I can come close to achieving my goals by my effort alone.  Secondly, due to quick changes in the surrounding environment, I often have to change my goal subtly.  Additionally, I have no time to share my goal with someone and worry whether or not I can achieve it.  I believe that there is not time to share something with others when someone is earnest and serious about it.