If you want the bleak truth about what your future will very probably be like, go with being a pessimistic philosopher. But if you want to get things done, prevent things turning out too badly, and increase your level of happiness, don’t stare into the abyss too long – be an optimist, live a life which may turn out to have been based on illusion, and hope for the best.
If most athletes weren’t unrealistically optimistic about their chances of success, they’d never put in the training hours that result in a lucky few of them reaching the Olympics.
We systematically mis-predict what will happen in our lives. Unless you suffer from mild depression, chances are you will believe that good things are just around the corner for you. Those with mild depression are more realistic than this, and less prone to this sort of wishful thinking: they predict their futures more accurately. Those with severe depression, however, are unrealistically pessimistic about what will transpire.