Optimism.

From the way I think (and this is nothing new ), your perception of the world IS your world. That doesn't mean lie to yourself and ignore the bad. It just means be hopeful and positive.

That way, you can also enjoy life when the time calls for enjoyment and having fun. And when its time to work, improve, aid or help, or get involved in something not so positive, your attitude will carry you through and inspire those around you as well.