For any career developers working with people who will need to put in lots of work and determination to meet their goals this appears to be important advice that we could give: keep your plans to yourself. Otherwise risk losing your drive to complete your project.
Here's what Wray Herbert says about it in Newsweek: "Talking the Talk".
Here's what a couple of Canadian researchers say in the Vancouver Sun: "Keep your 'identity goals' to yourself, scientists advise".
Here's the research article by Gollwitzer et al: "When Intentions Go Public: Does Social Reality Widen the Intention-Behavior Gap?"
If anyone sees videos featuring Professor Gollwitzer I hope they'll tell us.
[My thanks to the "O'Reilly Radar" blog.]