Google Smart Brief and Leadership. It's a free email that they will send you once a day from Monday to Friday except holidays that has 6 or 7 articles (not terribly long ones, 3 minute read per article maybe) on leadership and ending in a quote. It has some good stuff on there. Even though I am not in a leadership role at my current job I continue to get this email because it has good stuff in it. Plus if you have linked-in you can post their articles to your linked-in feed and get some good visibility that way.