That means keeping them away from dangers like cigarettes.
If your teen starts smoking, though, it's time for action.
In this Medical Minute, Judy Fortin found a program that's helping teens kick the habit.
Cassie Graham smoked one last cigarette before starting her school day.
If the 17-year-old has her way, that'll be the last time she'll ever light up again.
"It's getting pretty bad lately. It used to be just like kind of a fun thing and now i have to smoke," Cassie said.
Cassie is determined to kick her pack-a-day habit.
She's among a handful of students at her high school in Fairfax County, Virginia, who have signed up for a 10-week smoking cessation class sponsored by the American Lung Association.
Counselor Tami Marcheski said, "The success rates for the program have been outstanding. 37% of kids have a success rate for quitting and around 60% actually reduce the number of cigarettes smoked."
Smoking cessation drugs, nicotine patches, and gum are not approved for those under the age of 18, so experts and students say support groups like this one are essential.
Cassie also said, "I don't feel like i'm the only one who has these problems of feeling nicotine cravings all the time."
With her friends by her side, Cassie wrote down her worries and, once and for all, threw away a bad habit.
"I can quit now," she said.
The centers for disease control estimates that 20% of high school students in the U.S. smoke cigarettes.