John Kotter has been studying leadership in CEOs for 30+ years and I found the following paragraph in his book titled "What Leaders Really Do" an excellent summary of his most enjoyable book.
"Most corporations today are overly managed and underled, says Kotter. Management and leadership have two distinct, fundamental purposes. Management is about coping with complexity. Leadership is about coping with change. Good CEOs and senior management effectively do both all the while knowing where their strengths and weaknesses lie. They take steps that span a career--and that at times are personally painful--in working to improve their weaknesses. The key, of course, is to perceive and admit them."