It has been common knowledge that you should tell about you goal you to get there. But it have proved it is not quite right.
When you talk about it then do not explain what your goal is but tell how you want to do to get to your goal.
That means you should not tell you will complete a marathon, you have to tell you need to run 5 times a week. Be the person you tell about pushing yourself. And remind you of your plan.
Do you have any questions please feel free to send an email
With Best Regards