Sam’s Club contributes only 12% of Walmart’s total revenue, but the warehouse club division’s $58 billion in sales makes it the eighth-largest retailer in the U.S. In fiscal 2015, Brewer managed to increase Sam’s operating income faster than revenue, which has been disappointing; same-store sales were flat. The Lockheed board member is investing in digital and going big on health and wellness, more than doubling the organic offerings at Sam’s Clubs.