(FORTUNE Magazine) – Natel Matschulat, 43 MOUNT SINAI MEDICAL CENTER

-- ''Marketing a hospital is a challenge because it's something that people don't really want to use,'' says Matschulat, the first marketing director for the big New York City hospital. That hasn't stopped her from touting Mount Sinai's medical staff and patient care with $2 million of television, radio, and newspaper ads. She says, ''We want people to think of us first if they ever do need a hospital.'' Matschulat made people think about New York as a vacation spot while she was director of the wildly successful ''I Love New York'' campaign. Born in Egypt and raised in Greece, the naturalized American went to college in California but dreamed of living in Manhattan: ''I would have been happy being a little mouse here.''

Augie Nieto, 29 LIFE FITNESS INC.

-- Nieto has peddled his way to success. The president of Life Fitness, a subsidiary of Bally Manufacturing, has sold 100,000 Lifecycles, computerized exercise bikes that display both rpm's and the number of calories the rider has burned. Nieto bought the marketing rights for the stationary cycle in 1978 and spent six years selling it to health clubs across the country. When he wanted to add a flashier graphic display to a new rowing machine, he signed up with Bally, maker of the hit videogame PacMan. A home version of the bike is already available, and the home rower will be out next year. ''We prove the success of the equipment in the health clubs,'' Nieto says, ''then we tailor it for the home.''

Peter Seligmann, 37 CONSERVATION INTERNATIONAL

-- As president of Conservation International, Seligmann recently arranged a ''debt for nature'' swap with Bolivia that erases $650,000 of foreign debt in exchange for the nation's agreement to preserve four million acres of forest and grasslands. Similar swaps with Ecuador, Costa Rica, and Peru are in the works. Conservation International can buy the loans at a deep discount from banks that despair of ever recovering the full amount. After leaving Yale with a master's in forestry, Seligmann spent eight years as director of the California Nature Conservancy, where he raised $25 million to protect rare habitats. ''There are so many agencies involved with conservation in the U.S.,'' he says, ''but there has to be a partnership between countries to really make a difference.''