"The time of the great darkness" was payback time for Lou Zambello '55. Instead of taking pills during his battle with clinical depression, he says, he discovered "a prescription for making yourself more mentally healthy: if you do good you will feel good."     Zambello, who claims he is "trying to be retired" while consulting in sales and marketing, and his wife, Kathy (McConaughy '56), volunteered to house a pair of businessmen from Tver, Russia, for 10 days last winter. The two Russians were part of a group of 12 who'd come to Amherst, Mass., under the wing of International Training and Development, a nonprofit organization in Amherst that specializes in training programs for foreign professionals in business development and fiscal management.     Zambello was so taken with introducing his two ITD guests to American life that he took on a workshop to mentor the entire 12 in operating their businesses. Amherst, he says, is peppered with Pulitzer Prize winners and professors from five nearby colleges. The one-time captain of Colby's basketball team said, "They get so tired of hearing professors talk that ITD recommended me, the dumb old jock."     "What do you want to be to customers with your business? What is the dream?" he challenged his 12 charges, who operate establishments ranging from a coffee shop to the largest bookstore in a city of 500,000. Each developed a mission statement--maybe four words, maybe a sentence. Group critiques developed strategies and tactics to support each mission so that each business could achieve the dreamed-of results, what Zambello calls "the score."     With a résumé that includes years as senior vice president of sales with Spalding Sports and with Avia and The Rockport Co., two enterprises under the Reebok umbrella, Zambello says he's addressed audiences of 5,000 at athletic footwear trade shows. "I had the discipline and the skills, the shake and bake and the dance," he said, "and after thirty-five years, you know something."     And what do the Russians know?     One told Zambello she's taking back L.L.Bean's golden rule to her employees: the customer is always right. She's going to change the whole culture to cater to the consumer, said Zambello, who felt he was a missionary helping people who are truly pioneers in how to run a business. Introducing vision and mission, brand-new concepts to his charges, "was so inspirational to me," he said. "Now when I get up in the morning, I'm happy to start that day."     The son of immigrants who was recruited by basketball coach Lee Williams, Zambello relishes telling how dean of admissions Bill Bryan '48 informed him he had been admitted "with the lowest board scores we've ever accepted at Colby." Recently the business major, former president of the Boston Colby Club and class president played a starring role in establishing the Lee Williams scholarship in honor of his late coach.     "It's one of those paybacks," he said of the scholarship effort. "I became MVP and captain and met Kathy, the winter carnival queen and girl of my dreams"--and mother of their three children and current partner in The Zambello Group, their consulting business. "You never get a chance to say enough thanks."