Colin Powell, in It Worked for Me: In Life and Leadership:
Leaders and bosses see qualities that separate some few from the crowd. What do they see?
For starters, they see consistently outstanding prior performance in different positions.
They see someone learning and growing intellectually, someone preparing for the next level, not just maxing out in his current job; someone who is ambitious, but not cutthroat.
They see someone tested by his assignments and challenges generally given to people with more seniority and greater experience, thus indicating early that he can probably perform well not only at that higher level, but at levels above that one.
They see someone reaching outside his comfort zone to acquire skills and knowledge that are not now essential, but are useful at a higher level.
They see someone who has demonstrated strength of character, moral and physical courage, integrity, and selflessness, and who will carry those virtues to the next level.
They see someone who is confident about the next step. His ego is under control, and he is mentally prepared for the added responsibilities and burdens of higher office. It won’t go to his head. He is balanced.