Here's what I know:
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2. Removing yourself from the situation helps alleviate this terrible feeling.
3. Surrounding yourself with happy, confident, caring and optimistic people makes you a more happy, confident....okay, you get the point.
I learned this lesson when I was in Spain back in May, studying abroad for 3 weeks. For part of that trip I was sad, homesick and basically hating Madrid. But when I found the right people and the right circumstances, I never wanted the trip to end. I took in every minute. I let other people's problems be their problems, and not mine. I made new friends.
Now, sometimes you don't have to change the people. Sometimes, you have to change their view, too. Stick up for yourself. Speak your mind. Be nice, understanding and kind. Spend time with people who are like this and influence those who aren't to do the same. There are times where I am just plain mean. I think mean thoughts; I say them out loud. I want to quit work/school/studying. I want to crawl into my bed and sleep for days; I want to lash out at my best friends. But when I stop and realize that the only thing I need to change is my attitude and my atmosphere, things get a whole lot brighter.
I remember that being mean does not make things better. Wishing ill of others, pointing out their flaws does not make yours disappear. And complaining about all the work you have to do does not help, by any amount, to accomplish it.
Put on some happy music (Christmas if you're one of those) and wear your favorite color. Dance around a bit; draw a pretty picture. Smile! And know the only thing that will change your unhappiness is you.