Why Be Negative?

First, I don't understand why people have negative attitudes. What good comes from always looking at the dark side of things? I mean the only argument I can find is that if you never expect anything or hope for something to happen, you can not be disappointed. Those of us that live our lives to this code miss out on all the joys life has to offer. How can you learn anything without disappointment? Through disappointment we learn the real worth of what we have and that which we seek. If you live in a bubble of pessimism you don't allow yourself to have hope or faith. What kind of existence is that? We need to believe, we need to let ourselves strive for things we want, we need to hope and try for something better. We need to have our hopes dashed every now and again. It makes us stronger. We learn from our mistakes in how we failed; in order to grow we need some disappointment. Stop looking at the glass half-empty. That glass is not only half-full but you shouldn't want it any other way. Meaning, in life look at the bright side of the events in your life. If something doesn't go the way you want it, try and correct it for the next time. Do your best to get something out of your failure. Even if that is a harsh word, it is a harsher world and the life lessons you learn will make it easier as we get wiser. Something I said a little while ago, "if the glass isn't half full, I don't want it" really makes a lot of sense to me. I think I meant that in this world the things worth striving for are worth the disappointment if you don't attain them. Because if you don't stop trying one day you will get what you want. This life is yours, and yours alone.