Answer:
I think the most difficult part about being a teenager is just trying to fit in. No one wants to be left out of deemed "uncool." Therefor many teenagers do things that they won't do, just to try and fit in with the rest of their peers.
Step-by-step explanation
I am currently 17, and the biggest example of this that I see at school is vaping. Every time I walk into a bathroom there is other students in there vaping in a stale. I have seen countless times people I know who wouldn't vape do it just because they want to fit in and be accepted.