While I know it's cool these days to make fun of the Bible, last night a preacher gave a passage that's pretty badass:
And the King of Israel said, “Tell him: ‘One who puts on his armor should not boast like one who takes it off.’”
- 1 Kings 20:11
The sermon was about boasting, and the pastor was talking about the people who talk about "OH I'm going to do this and OH I'm going to do all this wonderful stuff and OH people are going to be amazed at all the stuff I'll do!"
Essentially, stop bragging when you've got nothing to brag about. Don't talk about what you are going to do... DO IT. Then, once it's done, you can talk about it, critique it, test it to see if it was a success or not.
The guy going out to the battle shouldn't say he's going to win the battle. The guy who has come back from the battle, alive and still strong enough to take off his armor, that's the guy who gets to tell the story.