I've always been a pessimist but lately i've been seeing how my negative reaction is influencing the younger people around me and I want to be more positive around them. But I have a lot of peerse around too and they've known me for a really long time and they call it being fake. What can I do to not come off as fake but still change my attitude to benefit the kids?
Only way to do that is to try to be a little more optimistic thinking wise, but try to keep it real when you speak to others. If you're usually the person who says "it won't work", "that would be boring", or anything like that, try to adopt more of a "maybe" attitude to start off with. Say "it might work" or "how about we try and see?". If you go on this agree-happy streak people will be thrown off by it, so unless you actually believe something is a great idea, don't say it definitely is. xD
That all being said, if you're going to change yourself, try to make this change for yourself first. I can understand that you don't want to negatively impact anyone, but if this is who you are and you actually aren't going to adopt any of these new views and thinking ways, it's ultimately not going to benefit anyone for you to pretend that you are.
Being real and being yourself is the most important thing. It isn't real unless you actually plan on accepting these changes within yourself, and no matter what, people will be able to tell that these efforts aren't "you". So, if you plan on being more positive, stick to it. They will adjust.
Just do what you feel is right. It is not being fake if you rather try to look at things in a more positive light. Who knows maybe your life will seem brighter also with the positive outlook. I would not worry too much on my peers if they can't understand then maybe try to explain why your doing it, but if they can't come to terms then maybe they weren't "real" either and I would move on.