Fifteen is the age many young people lose interest in after-school sports and activities, studies show.

Because of the brain benefits these experiences deliver, clinical psychologist Kathryn Berkett urges parents to encourage their teens to push through potential boredom and discomfort.

"That's literally the most important thing for our brain - learning how to push through tolerable stress experiences," she told RNZ's Nine to Noon.

Listen here on Nine to Noon.

'Tolerable stress' is the kind of stress that pushes us out of our comfort zone at the time, Berkett says, but, like a roller-coaster ride, delivers a rush of brain benefits after.

"Your brain says 'you've freaked me out', and then it gives you a rush of dopamine, which is our buzz hormone. Afterwards, you go 'oh my goodness, I did it' despite the fact that you may not have actually enjoyed that moment."

Educational psychologist Kathryn Berkett Photo: Supplied via RNZ

Parents need to try and assess whether the activity they're teen is wanting out of is tolerable or truly intolerable.

"It's positive if it's tolerable but it's negative if it's intolerable stress."

Berkett pushed her own daughter, who excelled at school, to continue karate classes after she started losing interest.

"I was very, very determined to make her keep going because it was where she was experiencing failure. Even though that sounds strange, it's one of the most important things we can ever learn.

"Because she wasn't [experiencing failure] at school, I really wanted her to stay so I sort of cajoled and bribed, and I made sure that she was going despite the fact that she mostly didn't like it … I knew the outcome [would be] really positive."

Teens should know that their parents value their continued involvement in activities, Berkett says, but the participant needs to be getting something out of it as well.

"I've never done music and I wanted [my kids] to do it so I pushed them a little bit but then I could see neither of them were really buzzed about it."

In the teen years, as hormones surge, parents are naturally "pushed to the outer circle" as young people seek their identity as part of a new tribe.

Understanding those dynamics - how teen girls "fall oxytocin in love with each other" and teen boys crave testing their physical strength, for example - increases parents' capacity to encourage their children, she says.

For the developing teen brain, almost any kind of activity is better 'than the "instant and unpredicted dopamine activation" of being on a device, Berkett says.

Once a teen has gone through with a class or activity they weren't really into, Berkett suggests checking in later in the week, pointing out any positive effects observed.

"Try and get them to process that the after-effect is worth the potentially not-positive [feeling] in the moment. That's a really important thing, to show them that [the activity] was fun. They did have fun." - RNZ