To be a good leader you must first be a follower. These words were passed down to me years ago and still ring true. To lead and mentor successfully, having a strong foundation and understanding to base your teachings on is important. Unless you understand the requirements for team collaboration, it will be very difficult to be a great leader. Regardless, it takes many years to learn and embrace the principles required to lead a team and mentor future leaders.
The learning aspect of leading, knowing when to humble yourself, and gaining your team's respect are things you cannot pickup in a class. While they sound easy, they take time. After decades of leading and mentoring I still learn from my teams.
When I say "humble yourself ", I mean be reachable and engaging. There's nothing wrong with getting into the trenches with your team, rolling up your sleeves and passing down knowledge. Never ask someone to do something you haven't done, or wouldn't do yourself. If you are able to earn your team's respect the possibilities of what can be accomplished are endless.
I believe that there is no end to learning how to be a good leader and person. People I have had the honor of knowing, who have mentored me throughout my life have made this very clear. Even after retiring, there are inspirational people that readily admit to still learning lessons on leadership.