Optimism is the faith that leads to achievement.

 —  Helen Keller

Optimism is a mental attitude reflecting a belief or hope that the outcome of some specific endeavour, or outcomes in general, will be positive, favourable, and desirable. 

Wikipedia

I'm all for being realistic, but how many memorable achievements in the world have been down to being realistic. We've seen and heard the stories of individuals with crazy ideas and who don't  stand a chance in the world's view. The odds were stacked against them, and if we were gambling folk, our money would be on the other guy. They won, and they prevailed. It's unusual, but these situations do occur, but I wonder what would have happened if they discounted the possibility. What if their mindset was negative and defeatist?They could render a positive outcome negative because their approach to the problem was contrary to what was expected. Numerous scientific studies are proving the benefits of optimism, but I won't even go there. We've all benefited from its power, so why don't we use it more? 
Because it's hard work.
I use it every time I start working on a story idea. I'm more or less a pantser - an author who writes without planning. I will have the stories beginning, middle, and end. The connective tissue - narrative cohesion is required for a story to work but at this stage, I don't know what it will be. But I know I can do it. I have missteps, confusion, and frustration but the bedrock to all that is my belief I will prevail.

Optimism is misunderstood, and I see how people use the concept in the worst possible ways. It won’t force you to do anything, but it will make you do it better as an optimist than over a pessimist. Another thing that trips up most people about optimism and any concept for that matter that could improve your life is their tendency of taking the wrong advice that is not believable, realistic or confirmed by your experience. I'm a speculative fiction author, so my beliefs systems are crazy varied and weird. So if you ask me if aliens live amongst us or what my beliefs are on how far we can go as a species, you're toes would curl with what I believe. So no matter how science is confident in its methods there are many things that they cannot completely understand. Contrary to what most of us think there isn't always evidence to support the decisions we should make. What I'm saying is if you don't believe in or have experience in a particular area, with some research and due diligence you can have an opinion, make a decision.
Optimism doesn't mean you will get positive results in everything you do. It's not about that. It's the edge it gives you so that you can approach life as the best version of yourself at all times. It's not about making positive predictions, and then when the results aren't favorable, you start talking about the problems with optimism. The problem rests with you. You win some, and you lose some whether you are an optimist or a pessimist. 
The trick is when an optimist fails they look for a lesson to be learned. As Napoleon Hill wrote, Every adversity, every failure, every heartbreak, carries with it the seed of an equal or greater benefit. 
Take the hit, reframe the experience and apply it to the next challenge.
I won't tell you anything here I don’t do myself. None of this is easy, and my results will vary dramatically just like yours, but we are in this thing together. Just promise me. Never, never give up.

Peace, Love and Power

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​​​​​​​Kwa Heri, Kings and Queens