Being Slightly Delusional is a Good Thing!

Some studies indicate if you're moderately overconfident, you'll choose more challenging tasks and this study shows it's an advantageous attitude to have.

If more challenging tasks provide more accurate information about ability, people who care about and who are risk averse over their perception of their own ability will choose tasks that are not sufficiently challenging. Moderate overconfidence is both pervasive and advantageous, but many people maintain such beliefs by underweighting new information about their ability. Source: "A Model of Overconfidence" from IZA Discussion Paper No. 4285, July 2009

Increases your productivity

Recent studies report that productivity increases under total  reward structures than under piece rate reward structures.  In "maze studies," people exhibiting progressively higher degrees of overconfidence solve more mazes. This result shows a positive aspect of overconfidence, which usually has been examined in its negative aspect as an expectation bias. Source: "Overconfidence Increases Productivity" from ISER Discussion Paper #0814.

Will this hurt you in terms of teamwork?

Overconfident workers are actually better for teams. Underconfidence is what causes problems.

Laboratory experiment to study how perceptions of skill influence teamwork, team output is increasing in skill and in effort, skill and effort are complements, and workers’ effort choices are complements. The presence of overconfident workers in teams is beneficial for firms since it raises effort provision and team output. In contrast, underconfidence is detrimental to firms as well as workers.

But don't be extremely overconfident.

Overestimation of ability raises utility by deluding people into believing that they are more able than they are in fact. Moderate overestimation of ability and overestimation of the precision of initial information leads people to choose tasks that raise expected output, however extreme overconfidence leads people to undertake tasks that are excessively challenging.

Go out in confidence and MAKE it happen!