Rarely does a two-week vacation change your life—much less those of thousands of others—but that's just what happened with Don Schoendorfer. The Orange County, Calif., engineer was traveling through Morocco in 1977 when he saw a sight that would haunt him for years: a crippled woman crawling along a dirt road. "In America we don't know what it is to see people dragging themselves over rocks because they can't afford a wheelchair," says Schoendorfer, now 55, who vowed that day to somehow ease the suffering. "But it's a way of life for millions of people."

In 1999 Schoendorfer made good on his pledge, launching the nonprofit Free Wheelchair Mission with 100 chairs he assembled in his garage. (It took him a year to perfect his lawn-chair-and-mountain-bike-tire contraptions, which are now made in China for about $30 each.) Since then the married father of three, who quit his job in 2001 to work full-time on the project, has overseen the distribution of 25,000 of the devices in countries from Angola to India. "I almost lost the desire to live," says grateful recipient Hao Chong Lan, 44, of China's Henan province. "You let me taste a brand-new world."

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