It's no use denying it. The world is full of idiots doing stupid things. So if you allow yourself to get depressed and disillusioned each time an idiot does something idiotic you're in for a lot of depression. This is clearly futile. Does it make the idiots realise what assholes they are? No, if it did they wouldn't be idiots. So the world will go from having just an idiot, to having an idiot as well as a depressed person.
The solution to this problem is simple. Don't let the idiots bother you. They're the idiots, they're the ones who should feel bad - not you, so just ignore them. Ignore the idiots.
A lot of people spend their lives indulging in feelings of guilt and remorse because of things they did in the past or yesterday night. While this makes great stuff for novels, it is not the solid foundation upon which happiness is built.
After all, whenever we make a decision we do what we think is the best. We may realise and admit later that what we did was wrong, but why regret it? Why should we regret that we did what we thought was the best thing to do? If it had happened today, we would have acted differently, but it didn't happen today. And even if it had we might realise tomorrow that we still didn't do the right thing.
We all know how embarrassing life can be. We might say the wrong things to the wrong people at the wrong occasions. We might fall in love with the wrong people for the wrong reasons. But why should these things be embarrassing? Couldn't they be funny instead - looked at from another perspective? If we see our life as a story that's slowly unfolding, shouldn't we appreciate it when the plot thickens?
After all, what kind of life do you want to live anyway? Do you just want a quick and painless life? Isn't the events in your life, however embarrassing, tragic or cruel they may seem, a sign that life indeed is flowing? What do you want in your veins, blood or chicken soup?
Do not say to yourself: "Well, all my problems will straighten themselves out as soon as...". If your life is not good right now then do something about it right now. For the chance is that when you have finished your education, got a steady job, found a girlfriend, moved to a new apartment, or whatever your current goal might be - a host of new problems have entered your life. This way the moment of your happiness is postponed indefinitely into the future.
When you're saying these things you are in fact making excuses to yourself for living a miserable life without doing anything about it. Do something about it instead.
Okay this one is an oldie, but you simply have to. Some people seek the love of others to compensate for their lack of self-confidence, but this strategy is doomed to failure. Then, how do you start liking yourself? Well, I'm afraid this is where my expertise ends because I have always kind of liked myself.
To be frank, all of these points require some restructuring of the way you view the world and yourself. This might not be an easy thing to achieve, but who said the road to happiness was paved?