Hi, Your feeds and negative feelings are nothing but habits.
The first thing to realize is that they are all thoughts, they are not you or who you are. For example, you may have a thought that says "You will fail a test". It is not reality, it is only a thought. Put yourself in the observer's seat and watch your thoughts, good and bad. When your observer catches a negative thought, thank it, and let it go. Say: "Thank you, negative thought, but you no longer fit here." Anther thing I like to do is use this simple mantra: "Everything always works out for me". After a while, it becomes true!

Hi! Your feeling negative is a choice in which you, yourself, make. And when you feel negative you will be negative, others will also feel your negativity--which is NOT good at all!! Be Thankful and grateful with what you have, and for whom you are, count your Blessings, you are healthy, you are alive, you have a roof over your head, food and clothing, the list goes on. Look for the Beauty in each new day, the sun, flowers, blue sky, birds signing etc. People are homeless and living in the streets--you are not. Begin being Thankful for that. Write down all the wonderful things you have and are and begin to fucus on that. You will succeed!!! Smile and Be Happy.

I totally recognise your feelings! What helped me very much was to simply write down all the nice/fun/pleasant things that happened to me that day. For instance the fact that you greeted someone in the corridor of your school and this person greeted back. Or that you had a laugh with your friends, or you had a good grade at school, or you had watched your favourite tv programme. Just those small things. And you'll have bad thoughts anyway, but let them pass and focus on the good ones. I noticed that after a week this became much easier, and things that bothered me at first seemed not even worthy to think about any more! You'll remember the good things, so that you feel more satisfied and happier at the end of the day! I hope you succeed too, good luck!