We do much of what we do because we believe it is the right, honorable, and proper thing to do. Most of us will welcome the opportunity to take on a thankless task because it validates us as a good person. It's a powerful value to appeal to when trying to influence people. Long-term investments are also important to us. To influence behavior and get people to do what you want them to do, get them to see what the situation will look like 2 years or 5 years from now.
Imagination is extraordinarily powerful in influencing subsequent patterns of behavior.
You can also influence people by showing them the downside risks of failing to engage in the behavior. Whether they believe you or not is a matter of trust and credibility. I tend to offer a positive reason, followed by a negative consequence of failing to do what I want them to do, followed by another positive reason. This allows people to consider the negative consequence in their decision calculus, but rationalize their behavior by thinking they are doing it for the positive reasons, not the negative ones. This is well documented in the literature in social psychology.