You can engage in all the self-directed learning you want today by reading a million books or signing up for courses, conferences and seminars that you attend. Will those help you grow? Sure; you’re consuming information that will help you grow your knowledge in particular areas. What do you do with that new information, though? Sometimes you apply it; sometimes you forget it within your busy life. Coaching, on the other hand, helps you synthesize what you consume and allows for a very personalized exploration around values, strengths, areas for improvement (and more!) You don't have to take my word for it though - check out this TED talk by Atul Gawande or watch some of these video testimonials collected via the International Coaching Federation (ICF).