If you want to accomplish something, it makes sense to tell people about it. After all, you might be able to collaborate with someone already working on something similar, or gain some ideas and insights from someone who has done it before. If nothing else, you’ll get some moral support, and be held accountable now that other people expect you to do what you’ve publicly committed to doing.
The problem is, we humans don’t seem to work that way. In fact, sharing your goals often has just the opposite effect: when we tell people about doing something in the future, we’re less likely to actually do it. After all, we’ve already gotten part of the benefit: recognition, praise, and support from those around us for even thinking about attempting something. Since our brain’s pleasure center has been mollified, you lose some of that fire to actually go out and do it.
Derek Silver explains some of the research behind this: