The following commentary comes from an independent investor or market observer as part of TheStreet's guest contributor program, which is separate from the company's news coverage.NEW YORK ( TheStreet) -- A core task of every leader -- manager, coach or parent -- is to accelerate the growth of those in his or her charge. Most leaders tackle this challenge by direct instruction -- telling people what to do. Direct instruction is also the method-of-choice for most training departments. Although instruction is often necessary, it is rarely sufficient for teaching people to cope with life's challenges. Experience is life's great teacher. Just before I left graduate school, my wife's manager asked for my advice on handling a problem supervisor. It was a very simple question. By that point, I had read more than 5,000 articles on leadership, yet I had no idea how to answer his question, because I had never managed a supervisor. I learned that knowledge without experience is of no practical value. Disseminating information is relatively easy. But how do we, as managers and parents, accelerate growth through experience? Humans grow from diversity (i.e., many different kinds of experiences) and adversity (i.e., tough, nasty times). Successful managers and parents accelerate growth through diversity and adversity.