Negative talk is one thing, but the bigger issue, usually arising from that, especially in children and young people because they are very receptive and still working out their identity, is negative self-talk. Other people can spend only so much time in bringing you down, because they also have other things to do, but your inner critic is always with you 24/7, so it is him you have to be most worried about. Nobody can talk you down, unless you let them, unless the inner critic makes the agenda of some critic from outside his own.