Persuasion. The psychological technique, not the Jane Austen novel. How do we persuade people to exhibit a particular behaviour?
According to Wikipedia persuasion is the process of guiding people and oneself toward the adoption of an idea, attitude, or action by rational and symbolic (though not always logical) means. The Wikipedia article cites lots of techniques and barriers to persuasion, but misses the big one as far as I can see.
In my experience the best way to persuade someone to pursue a particular course of action requires one fairly straightforward question to be answered;
“What’s in it for me?”