Be accountable for your Mistakes
You already know that failure is a crucial and almost always necessary part of the path to success. However, there's more to failure than just learning from your mistakes -- there's owning up to them, too. Sometimes failure will come because of your own mistakes, sometimes it won't, but regardless of why something didn't work out, you must own the problem.
There are serious long-term implications for not owning up to your mistakes because being a leader means you're participating in a critical and visible position. Your reputation is your brand, and while no one expects you to be perfect, everyone expects you to be honest.