Chances are, you have people in your life whose behavior you wish would change. Your romantic partner might be putting on a little weight. Your parents may complain too much. Your best friend won’t look for a new job, even though she hates the job she has now.Once you notice these annoyances, it is natural to want to push people to change. Is it actually possible to change someone else’s behavior? Should you even try?It turns out that you can help people to change their behavior, but there is a limited amount you can do without their help. That is, there is some validity to the old psychology joke:Q. How many psychologists does it take to change a light bulb?A. One, but the light bulb has to want to change.The best way to help other people change is to learn about how to change your own behavior. The more you know about the factors that drive your own behavior, the better you can use the same principles to help other people change.MORE: If Your Partner Changed, Would You Be Happier?For example, human beings are a remarkably social species. We are wired to adopt the goals of the people around us. That means that there is something deeply right in Mahatma Ghandi’s exhortation to be the change you want to see in the world. (The original quote was, “If we could change ourselves, the tendencies in the world would also change.” Truly fitting.) When you act in the way you want others to behave, you are helping the people around you to unconsciously adopt the goals you are pursuing.People are also strongly driven by their environment. We generally do things that are easy to achieve and avoid things that are hard. That means that you can help people to change by removing temptations from their environment and replacing those temptations with items that promote desired goals. Many cities have taken this proposal to heart and have instituted bike-sharing programs that make it easy for people to leave their cars behind and to pedal from once place to another.Unfortunately, there are limits to what you can change about another person without their cooperation. Unless someone is willing to really commit to a new goal and make plans that will help them achieve that goal and turn it into a habit, that individual is unlikely to make lasting changes in her life.And that leads to the question of whether you should try to affect other people’s behavior.The answer there is more complicated.I am a big fan of communication. If you think that it is important for someone in your life to make a change, then talk about it. Do not try lots of indirect ways to get them to change. Most people quickly become aware of your attempts to influence what they do (and may reject or resent them). So, don’t assume you are being clever by hiding the Ben & Jerry’s or suggesting lots of early morning walks on the jogging path.MORE: How to Break Bad Habits and Form New OnesIt is fine to let the people in your life know that you care about them and stand at the ready to help them in any way you can. After that, though, you have to give them some space to decide whether they want to change.And while you’re at it, take some time to look at your own life. The sad fact is that it is often easier to try to fix other people’s problems than it is to fix your own. So, as you start to learn about principles for making changes, practice by applying them on yourself.