No matter who you are, no matter what you do, no matter what you say, someone is watching you. You may not know who, you may not know when, you may not know why, but there is at least one someone watching you.
Your example counts.
In the case of us as teens, we are very often looked up to by younger kids, they watch us, and no matter what you think of yourself, they want to be like you. They want to dress like you, talk like you, act like you, and do everything that you do. And not only are we looked up to by younger kids, but by peers as well.
For example, think of a popular girl. Someone who most everyone knows about. Do you know how many kids, and even teens, want to be like her? Don't you see how she has made herself a standard of "coolness"? The world thinks she is just about the coolest girl on the planet, so what happens? Basically everyone wants to be the coolest girl on the planet, right? So people begin to copy her, they begin to try to be like her: talk like her, dress like her, act like her...etc.
What do you think now? Are your standards for yourself the same as the standards that you place before others? In others words, do you practice what you preach? For example, do you look down on cussing, and then go out and do it yourself? Or, do you say that wearing sleeveless tops is immodest, and then you go and wear them yourself?
Examine yourself. Is what you wear what you want those around you to wear? Is what you say what you want those around you to say? Is what you do what you want those around you to do?
You are being watched. Your example counts. When you get that through your head, you act differently, you talk differently, you dress differently, you change.