"You can start by finding a “truth teller” who will share honest feedback with you"

"Why are weaknesses and fatal flaws so hard for us to spot in ourselves? Here’s our theory. Strengths are seen as a direct outcome of some specific behavior exhibited by the leader. For example, they are extremely effective at solving problems and can point to specific instances where their quick thinking saved a project. Or they’re extremely good at marshaling their team to produce excellent work, and have seen the impact in the form of happy clients or industry awards. The leaders recognize something they do that produces a positive reaction, followed by a positive business outcome.
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Weaknesses — especially fatal flaws — are the opposite. Fatal flaws are “sins of omission.” They’re a result of inaction, of the leader not doing something. In our assessments, some of the fatal flaws we see most often are a lack of strategic thinking; not taking responsibility for outcomes; and not building strong relationships. We occasionally do find leaders whose fatal flaws are “sins of commission” — like a boss with a terrible temper, or an executive who lies — but those people are (fortunately) very rare.
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Because most fatal flaws are sins of omission, they are harder for to see in ourselves. The result, after all, is not visible. It’s a deal that never happens, or a project that doesn’t exist. These leaders are simply not making things happen.
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Becoming More Self-Aware
There are several ways you can learn to identify your weaknesses, and start to figure out whether they are serious or mild.
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You can start by finding a “truth teller” who will share honest feedback with you.
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Think about it. If roughly one-third of leaders have a fatal flaw and you are sitting in a management meeting, look to your right and then to your left. As the old joke goes, if in your opinion, neither of these two colleagues has a really serious weakness, then the laws of statistics suggest that you do."

Trechos retirados de "Most Leaders Know Their Strengths — but Are Oblivious to Their Weaknesses"