I haven't watched this (I'm on a bus, bandwidth concerns) but the title just made me think: "yes, keep your goals to myself. In a diary. That way I won't be demotivated by premature announcement, yet I'll be bursting to have something to show when I make progress"

Promissing to ones self, for me at least, is a motivator because I trust myself more, and the trust is reinforced as I complete goals. But announcing "I'm doing this thing" either causes anxiety, or demotivates nectar is already our there, as the article describes.