Optimists and their optimism are the key components in progress.
Just to clarify and leave no doubt about My position: pessimists and their pessimism are NOT the key components in progress.
Though the position is as unassailable as the idiocy of Our government, let Me provide another angle of support. From bmindful, a website focusing on the positive outlook of Life (and often so "touchy-feely" it makes My teeth ache), comes this article. Though it focuses on procrastination, it clearly delineates how an abundance mentality (product of optimism) is far more effective in getting things done than a scarcity mentality (product of pessimism.)
...Abundance means 'The property of a more than adequate quantity or supply' and to really take advantage of all that is available to you, you really do have to have a handle on this extremely important way of thinking.
The exact opposite to the abundance mentality is the scarcity mentality. Amongst other things this mentality breeds fear, jealousy, spite and selfishness leading to insecurity and lack of self worth due to your belief that opportunities are lacking and you have little choice or freedom in your life. The scarcity mentality leads to you seeing nothing but obstacles and problems.
Without saying anything more we can see the negative side effects of the scarcity mentality, but how is the abundance mentality superior? It leads to opportunity because you believe it is everywhere, riches because you believe there is plenty to go around and enjoyment because you are able to celebrate other people accomplishments instead of loathing someone for stealing your 'piece of the pie'.
So how does this all relate to procrastination? Well, people with a scarcity mentality usually procrastinate because at first glance the task they should be getting on with seems all too hard because of all the perceived obstacles and problems. With an abundance mentality you look at possibilities and opportunities rather than obstacles and problems meaning you don't have any reason to put it off, and a few good reasons to get on to it right away!
There is a need for seeing obstacles, for it can best delineate how an effective plan can be implemented. But to see only obstacles and call that "reality" is like seeing garbage and calling it "food".
One more analogy: Optimism is the accelerator, steering wheel and the engine; pessimism is the brake. Overusing the brake--or using only the brake--leads you nowhere.
The Jenius Has Spoken.