What have you learned about leadership in your experience?

In the same way that one might say "I will never do (or) I will do what my parents did" over the years of one's working career, one will have the opportunity to work for good and bad leaders. Both experiences can be good. With the bad boss (or leader), you are intent on ensuring that you never behave in the same way. All the things that they have done which undermine their staff and destroy any motivation are the things, if you are sensible, that you will avoid.
Similarly, working for someone who is inspirational, is an opportunity to learn and grow yourself as a leader. So, you can cherry-pick the good and the bad and use this as the template on which you will base your own style of leadership. Perhaps the most important thing I have learned is to listen. You will learn from your colleagues, from your staff, from your superiors and from your juniors. This will help you to keep your finger on the pulse when any changes in the organisation are looming and to know your staff well so that you can get the best from them.