Last Week's Definition:
Being an effective leader requires an understanding of your role in the larger picture of the project or company, a tuned sense of one's shortcomings and prejudices and a realistic view on team equilibrium. Groups cannot be expected to function optimally immediately, an good leader allows a team to mature before judging too harshly.
Optimal leadership includes self-improvement paired with the work of the group. One should recognize the limitations of the self and initial group and set clear goals for outcomes, learning over time to work better as a group and as a leader.
Boyatzis reminded me of the objective of self-awareness and analysis, finding the traits that could use improvement and focusing on improving those.
Boyatzis, R. E. (2006). "An Overview of Intentional Change from a Leadership Perspective." Journal of Management Development, 25(7), 607-623.