You have a great idea that you wish to put into action.
People will do many things to stop you before you begin, if you leave the door open for them to do so.
Say you have a great idea for a project. Before you start it though, you run the idea by some friends to get their input. They trash your idea and convince you not to do it (or ruin your confidence in it enough that you discourage yourself).
Let's say instead that you just started the project, and once you were halfway done, asked for input. The responses would be much more positive just due to the fact that the project existed at that point. You had taken action. It's tangible and self-evident.
Ideas are merely talk: cheap and useless. Once you begin to act on an idea, you now have something that exists, you're a creator instead of merely a talker/thinker/dreamer.