It turns out you are neither always one or the other.
You can be optimistic that your football team is going to win but pessimistic about healthcare reform.
What makes someone optimistic then?
Optimistic people believe in more possibilities. They believe the world can be a better place and that people are doing the best they can.
It’s hard to stay optimistic all the time (and to be pessimistic too). Much like the moon, you are either waxing or waning.