In life, you do some things because you want to, and you do some things because you are forced to. There are some things which your mind forces you to do, because for the lame reason - others do it. Yes, out of peer pressure.
Peer pressure is neither out of your own conscience, nor is it forced...but quite a mixture of the two. When you don't have a control over your own decision making, and just tend to do what your peer group does, you are under peer-pressure. Though there could've been a zillion good qualities to pick from a peer group, the Gen-X usually fall prey for the bad ones.
People fall a prey to this because they feel that they would fall out of the group, in which they so really want to be. A reality check would have reminded them that, 1. they can as well leave the "group" if it is spoilt, or 2. stay in the group without gathering those habits and let the others know that he is fine without practicing them. It is "cool" to be a teetotaler, not a smoking/boozing/doping out of control inhuman idiot.
Nearly half of worlds' smokers/drinkers pick the habit of drinking or smoking (or even worse, doping) during high school or college. School and colleges are two of the most probable places where teenagers are likely to come into a mix of people from many many backgrounds. Its a new mix, and the character building takes place. They find new friends, form a group, get a new unique feel, project themselves as being the unique "cool" group. And, suddenly, some of these groups get the idea of doing something (to start with) foolish! Say, playing pranks on people... Well, till some level, that is fine... Some pranksters stick to that level, at max. But then there are some other ones, who try to cross that fine line between foolish and wrong. They fall into the spiraling, high gravity suction of really dumb things. I stop you to ask, if you really want to be "famous" for all your life, how in the bloody hell is dying (by means of alcohol, tobacco and drugs) gonna help you?
Peer pressure is not just about all those things at all... There are many cases when someone says something, and everyone agrees with him/her, even though there might have been some better suggestions yet to surface. But, people assume that the hot shot has spoken, and that is the best thing! How many times have you just agreed to do what the group does, even though you had no idea what it was, or wanted to do something else? People have done things as insignificantly as eating dinner at a different place to cosing the wrong course. Some people want to become engineers, some people become engineers because their neighbour is going to be one. He will get a new pair of shoes because everybody else in the group is. She will buy a doll, because all her classmates own one.
Really, is this what you live for? Catching up on what others do? Sometimes, you need the blinkers that the horses wear to look straight at your own path and reach your goal. If the people in your group are dumb enough to fall for something dumb/stupid/foolish/unethical/bad/sad/unnerving/crazy, you need not be another link to the chain. You have the right to take your own decision. By that, I mean, do what you really want to do, not your neighbour/groupmate/competitor.
Sometimes, you do fall for peer pressure. It's a sub-conscious act. But, at one point, you need to have a reality check. Are you where you earlier thought you would be? Are you on the right track? Are you ticking off the milestones on the path to your goal? Or are you knocking on the doors of nothingness in the middle of nowhere? You can change the mindset of some who have fallen prey to it, or, just admit that they are irreversible and let go of them. Sometimes, you have to save your own head from getting chopped when the farmer is looking for the rodents.
Get real, be yourself. If you wanted something the way you wanted it to be, and if it is for the betterment of you and the people around you, you must have it!
Allow your peers to elevate you, not bring on your fall...