“JUST SAY NO!” That’s often the advice parents give teens about how to deal with peer pressure. It seems simple, but sometimes saying no isn’t so easy. Young people might be worried about being teased, feeling embarrassed, or losing their friends. Setting limits — and sticking to them — can actually be a major challenge for teens. Doing it well takes consideration, skill and practice.

As teens get older, they’’ll likely be spending more time with friends and on their own. Developmentally, that’s exactly what you’re supposed to do, and it’s an important part of becoming independent. But becoming independent also means making their own decisions about how they spend their time and what they do with their bodies.

Their friends might be experimenting with drinking or drugs, having sex, or engaging in other types of potentially risky behavior. Even if they aren’t directly asked to join them, they might feel pressure to fit in. But doing things to fit in is basically the opposite of true independence.

I tell young people that if they really want to be independent, it’s important to really think about their own values. They need to figure out what kind of behavior they’re comfortable with, and speak up for themselves. They don’t have to evangelize their beliefs or try to convince anyone that their way is the best way. They just have to act in a way that feels right to them and fits with their own values. And that means they have to spend some serious time thinking about exactly what their values are.

I explain that one of the easiest ways to get some clarity about your own values is to simply make a list. You could call it ’“What’s cool with me?” or “What are my limits?” I tell them to think about the big decisions that teens have to make and how they feel about them. Run through some realistic situations — it’s a lot easier to make the right choice if you’ve thought about it in advance.

For decisions about substance use, it helps to think in specific terms. Here are some things you could say to a young person: “How do you feel about smoking cigarettes? Is it something you never see yourself doing? If so, congratulations. You’ve just clarified one of your limits. Now think about other drugs, like alcohol, marijuana and cocaine. What are your own beliefs about using them? What will you absolutely not do? Are you willing to be around friends who are using them even if you’re not? Are you willing to get in a car with a driver who is high or drunk?

For dating and relationships, young people need to think closely about what they are comfortable with. When do they think is the right time to start dating? What exactly does that mean to them? What are they comfortable with when it comes to physical contact? Is making out ok? Touching? Sex? Where are their boundaries? Are random hookups ok with them, or do they want a long, serious relationship? These things can be tricky to figure out, but it’s a lot easier to think clearly about them in advance than when a cute person is whispering suggestions in their ear.

Now that they have a basic idea about their values, it’s time to think about how they’re going to communicate them to other people. Think about the reasons behind their limits and practice stating them out loud. Maybe they are on a sports team and would face penalties if they were caught. Maybe they don’t want to put their college plans in jeopardy. Maybe they have a family history of alcoholism or drug addiction and they don’t want to take chances with themselves.

Just like shooting baskets or solving algebra equations, setting limits gets easier with practice. Young people can rehearse on their own. Practicing saying things like “That’s cool if you want to do it, but it’s not for me,” “I promised myself I wouldn’t ___________ until I’m done with high school,” or even “I would love to join in, but my mom is really really strict, and I can’t take a chance on her finding out” can help. If teens are clear and firm when they set their limits, their friends will respect them, and they’ll feel good about being true to their own values.