Self-esteem is made up primarily of two things: feeling lovable and feeling capable. Lovable means I feel people want to be with me. They invite me to parties; they affirm I have the qualities necessary to be included. Feeling capable is knowing that I can produce a result. It's knowing I can handle anything that life hands me.
Switching from one career to another can be scary, but it also can be a thrilling experience. Look at it as an opportunity to really go after what you want to accomplish in life and make a difference in the world. The key is to take small, conscious steps and prepare yourself for a successful transition.
Leaders cannot work in a vacuum. They may take on larger, seemingly more important roles in an organization, but this does not exclude them from asking for and using feedback. In fact, a leader arguably needs feedback more so than anyone else. It's what helps a leader respond appropriately to events in pursuit of successful outcomes.