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If you were learning how to become a master carpenter, you would see every job as a chance to learn something new. It is the same in coaching. In fact each situation you put yourself in that really challenges you will only accelerate your development as a coaching leader. You might make a mistake or two, but we are not practicing to be heart surgeons here!
If you stay focused on individual and team performance and have a genuine desire to help people grow and succeed, people will want to work with you as you hone your skills. I probably make a rookie coaching mistake or two along the way, but no one ever lost their trust in my commitment to help them succeed. Trust is key. Trust in yourself and trust the process of coaching and you and your team will grown and succeed.