Do you believe that great leadership requires being an optimist? Can anyone become one?

When I was challenged with these questions, my mind initially went to, “It could be helpful for a leader to be an optimist, but not necessarily.” I knew the opposite; being a pessimist was not a quality I saw in any great leaders I followed.
I also questioned, “Can anyone become an optimist and do I really want to be that eternal optimist or have everyone around me be an optimist”? Well, what I learned was it depends on my definition.
A flawed definition
What prompted all of this for me was a couple of months ago, I heard someone speak on the subject of the importance of being or becoming an optimist. What I learned was my initial belief and definition was flawed.
Not that there is anything wrong with this, but when I previously heard someone is “always optimistic,” my personal bias went to that person who outwardly expressed “Everything is always good,” “Never had a bad day,” “It’s all good” or someone that looks at everything with “rose-colored glasses.”
I would often get a feeling of mistrust and wonder, “What are they hiding?”  Hardly an impression a great leader would want to portray. At the same time, I know I like being around an optimist way, way more than a pessimist.
Well, what was shared is the origin of the word “optimist” came from a Latin term that means “always moving toward the best outcome.” The speaker went on to say that an optimist doesn’t think any differently whether they are in a good or positive situation or a bad or difficult situation.
Optimists are always thinking of improving their or their team’s outcome and making the best of whatever situation they are in. A true optimist has faith that they can and will be able to work toward the best possible outcome. By this definition, the optimist naturally exudes a sense of calmness that makes it easy for others to want to follow.
So, now that I have locked in on this definition of an optimist, I will share my answers;
  Can anyone become an optimist? Sure.
  Does great leadership require being an optimist? Definitely.
  Do I really want everyone around me to be an optimist? Absolutely.