There are two types of people who will tell you that you cannot make a difference in this world: those who are afraid to try and those who are afraid you will succeed.
Surround yourself with positive people. Avoid those whose mission in life is to find reasons to disagree, argue and discourage you. Life is challenging enough without them!
Let no corrupting talk come out of your mouths, but only such as is good for building up, as fits the occasion, that it may give grace to those who hear.