Philosophy Question Thoughts

I have interest in the philosopher Leibniz. He believed in optimism and in that we live in the best world. I agree with his thoughts because if we are optimistic about things we will have a more positive outlook on our futures and become motivated to achieve what we want and do things in life that we want to do, as well as affect others around us in a healthy way. Therefore it's a win win situation for everybody. We benefit with a healthy attitude and people around us do as well. It's like if somebody next to you yawns, you yawn as well. It is a contagious act. Similarily if you hold an optimistic attitude others will, and negativey won't have to control everyone's lives. So my question is, what is the result of being optimistic? Will it get us further in life or will it hold other thoughts back by only focusing on the positives?