Persuading someone to do what you want isn't easy. Writer Daniel Pink points out that the real trick is to get someone to articulate their own reasons for doing something. One way to do that is to ask a couple of irrational questions.
Using the example of getting a teenage daughter to clean her room, Pink suggests starting by asking the person to talk about where they are on a scale of 1 to 10. For example, you could ask your daughter, "On a scale of 1 to 10, how ready are you to clean your room?" Once she responds, you can follow up with, "Why didn't you pick a lower number?" When she's forced to defend her position, she'll likely find that cleaning the room isn't that big of a deal.
Hopefully, you'll ferret out the daughter's reasons for doing (or not doing) something and convince them to do what you want. Pink notes that people tend to believe their own reasons for doing something more than yours, so your job is more about helping them convince themselves to do something than for you to convince them of anything.
Obviously Pink's exact rhetoric doesn't work in every situation or on every person, but the real trick here is to figure out what another person's motivations are. Once you have that, you can work with them to come up with an actual solution.