In addition to being an important driver of personal health, optimism has been cited as one of the most important qualities of an innovative leader. There's a pessimistic view, however.

Leaders who are too optimistic can actually diminish their team's morale and productivity. This is because excessive optimism (for example, a "we can do anything" mindset) comes across as blind to the inevitable challenges or ambiguity that a team may face along the course of a project.

According to Liz Wiseman, author of  Multipliers: How The Best Leaders Make Everyone Smarter, there are ways for leaders to avoid coming across as overly optimistic.

One way is to focus on the challenges that lie ahead for your team. As Wiseman reported to Quartz at Work, when leaders talk about the reasons an approach might not work, someone on their team is more likely to jump in and insist on why the team will succeed. It's a bit like reverse psychology.

Another way is for leaders to be more strategic in the questions they ask. Wiseman recommends asking questions like, "What problems do you see that I may be missing? Are there reasons we shouldn't proceed? And where might our assumptions be wrong?" Through this line of questioning, you as the leader acknowledge that there may be challenges, while also showing your confidence in your team to overcome them.

Nobody wants to work for or with Debbie Downers. But at the same time, employees want their managers to recognize the hurdles they overcome in order to help the team succeed.

The next time you want to encourage your team, express your confidence in their abilities while acknowledging that their may be struggles along the way. That's right. To be a good leader, you need to be a slightly pessimistic optimist.