Persuasion is a skill, and leaders need it as much as salespeople do. Two techniques are worth knowing. One opens with a request so large it gets refused, which makes the real request feel reasonable by comparison. The other opens with something tiny and easy to agree to, because a person who has said yes once tends to say it again. Neither one comes with a guarantee.
This is the short version. The full lesson, with the story behind it, is in the book.
Take The Summer Camp MBA with you, or get the field notes by email while you work through the lessons here.