NEW YORK ( TheStreet) -- When I was young, my father told me, "90% of success in life comes from just showing up." I think about that when trying to learn Chinese. I'm always searching for the best method or the best smart phone application. But recently a Chinese colleague told me, "If you just study for 30 minutes every day, you'll learn Chinese." He's right. I need to forget the perfect solution; I just need to show up -- every day.Today, the world is filled with leadership theories, tools and training classes. Enter "leadership" in the books section of Amazon.com and 95,000 books show up -- each one with a different theory. But for many managers, these provide little value; because many managers just don't show up. I once spoke to a private banking manager at a large South American bank. I asked him about his job. He proudly told me about his customers -- 14 of them. Curiously, that was about the same number that each of his direct reports supported. Then he told me about how he spends his time each week -- working with current customers and searching for new ones. But, what he did not say was most important. He did not talk about managing people. This is not an unusual example. It happens when the best engineers are promoted to managers. They continue doing what makes them feel proud -- engineering. Or, there is the sales manager who is too busy "serving the customer" to develop direct report sales skills or sales team teamwork. Is it a sales manager's duty to personally serve customers or is his duty to build a team that serves customers? Too many managers just don't show up.