-trying to fit in
-peer pressure
-abuse
-fun
-for the "high" feeling
-to be popular
-...uhh..idk..lol
Answer: Peers
Other people for example if they are smoking that can harm you by second hand smoking or persuasion for you to smoke.
Peers can also effect you emotionally by making you cry and angry.
Fitbits, smart watches and pe'dometers can monitor heart-rate.
I believe that 36% of 9th grade girls are likely to be involved in drinking, based on recent studies.