TRAIN your mind to see the good in every situation. It won't come naturally, you WILL have to work at it, but eventually it will become second nature and you will have joy in your life even when things aren't going your way.
Leadership is about helping and serving others. Empowering and bringing out the best in them. Positively influencing the lives of others is a key component of leadership. If you are not ready to do this, you are not ready to lead.