Being negatively influenced by other people is easy if you don't know who you are.
You allow for people to get into your head and mold you into what they want you to be rather than what you want to be for yourself, because quite frankly, you may be unsure of what you want to be after all. Not only does listening to other people before following your own heart ruin friendships, but it can also damage relationships and ruin your chances of cultivating something great with a person who may be more like you than you know. Influence isn't always a bad thing, but when you let people get in your head and skew the truth so that it benefits them and their relationship with you, it is extremely harmful.
Tell me this: Why would you allow a person to convince you into not liking someone else just because they personally don't like the person themselves?
Why would you let a few opinions dictate how you feel on a subject if you've never taken the time to study the subject on your own?
Why would you go along with supporting a candidate for office just because your parents told you to without researching the candidate for yourself?
These are all questions I want you to ask yourselves, because the point is, no one should be able to dictate your decisions in life except you.
If you like that girl and believe she's everything you've ever dreamed of and more, don't let your friends manipulate you into not settling down. If you want to befriend that guy/girl in class, but someone tells you not to simply because they don't like the person, see for yourself what the person is about before choosing to side against them. If your parents tell you to vote for a political party candidate because it's tradition, do research and make the decision yourself rather than voting for a potentially bad candidate simply because your mom and dad told you to.
Stop listening to all the voices around you telling you what to do and go with what your heart says.
I promise you will live a much happier life once you start living for yourself rather than living to please others.