"It was one of the best times of my life," David Hilmers said.
The mission-- investigate the effects of microgravity on living things.
In his career, he logged just under 500 hours in space.
PHOTOS: Dr. Hilmers, from space and around the globe
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Hilmers said each time he looked down on our world, he was reminded there was something far bigger, far greater that he needed to be doing.
"I grew up with maps spread out in my room and just looking at countries, and I was just fascinated by geography," Hilmers said. "My dream even when I was a small kid was to be a doctor doing global health."
Just months after that final mission on Discovery, the former marine and Vietnam vet enrolled in medical school.
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"Nothing really takes the place of seeing the smiles on the patient's face," Dr. Hilmers said.
Hilmers began the biggest mission of his life, treating men, women and children in impoverished countries.
"They are real people," Hilmers said. "They have real problems."
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Personal photos from those medical missions show the doctor at work, from Romania, where he helped children with AIDS, to war-torn Iraq and in Africa, treating tens of thousands of people in refugee camps.
Pictures show him making house calls in Ethiopia and in Nepal.
"Some of our patients just say we count the days until you return again," Hilmers said. "To hear those words come from people that we kind of think of as just the other guys, the bad guys."
Last week, Hilmers was in North Korea, helping hundreds there with a Hepatitis B outbreak that is killing so many.
"Although I have a lot of difficulties with the policies of the leaders of the country, it's not the fault of the people who are there," Hilmers said.
Dr. Hilmers hopes the acts of care and kindness he shows may do something else: heal relations with our enemies and to bring about peace.
Dr. David Hilmers is an American treasure, the world's doctor and lifesaver.
For all he's done, Dr. Hilmers gets this week's Foti High Five.
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