Sylvia Ann Hewlett, an economist and the founder of the Center for Talent Innovation, has studied the difference between mentoring and sponsorship and what leaders have to gain from the latter. She says it's important to seek out protégés who outperform, are exceptionally trustworthy, and, most importantly, offer skills, knowledge, and perspectives that differ from your own, so you can maximize the benefits for both parties. Hewlett brings real-world lessons from several successful pairings and tips on how to effectively launch and manage these long-term relationships. She's the author of the book "The Sponsor Effect: How to Be a Better Leader by Investing in Others."