(CNN) -- When Charity Tillemann-Dick was 4, her parents took her to her first opera.
"'Hansel and Gretel' was spellbinding for me," she said. "I knew I wanted to sing and that I wouldn't be happy doing anything else."
More than 20 years later, the petite blonde has performed in operas across the world, at the prestigious Franz Liszt Academy of Music and the National Palace of the Arts in Budapest, Hungary, the Kennedy Center in Washington, and at several popular music festivals in Italy. But last month, she sang for the most important audience she'll ever have -- the doctors and nurses at Ohio's Cleveland Clinic.
Belting out Gershwin's "Someone to Watch Over Me," she thanked them for performing a double lung transplant and open heart surgery in September that saved her life.
"It's always gratifying when you see a patient recover, but to have a patient recover this quickly and to this extent -- it is stunning," said Dr. Ken McCurry, who led the nine-hour operation.
"Even when she was lying there, and I was telling her what was involved in the procedure, she nodded and asked questions," he said. "She seemed, of course, nervous. But she was calm, focused."
Noticeably thin -- but looking much healthier than she did right after the operation, when she weighed 95 pounds -- the soprano serenaded her caretakers with Puccini's "O Mio Babbino Caro" ("Oh My Dear Papa"). The full-bodied aria reminded her of the last six years, she said. Its heroine pursues the object of her love, despite her family's fear that it could kill her.
At 20, Tillemann-Dick was told she had idiopathic pulmonary arterial hypertension, abnormally high blood pressure in the arteries of the lungs, which forces the right side of the heart to work harder than normal. It worsens over time. Eventually, her doctors warned, her lungs would give out.
Most people would be sad, depressed, overwhelmed, even angry to hear that news. Tillemann-Dick, whose full name is Charity Sunshine, did feel all those things, but not for long.
"I'm not going to say I didn't say, 'Dear Lord, are you freaking kidding me? Like, really?'" she said. "But when you're facing a challenge like this, it's important to plow through and do the best that you can and do what you want to do that's good. Otherwise you'd be in a sorrowful pit of depression."
Tillemann-Dick's view of disease as just another obstacle to be overcome may be partly explained by a look at her family, where high achievement is the norm.
Her grandfather was the late Tom Lantos, the longtime U.S. representative from California who was the only Holocaust survivor in Congress. Both her parents went to Yale; her father, Timber Dick, was an inventor and NASA engineer and son of the first female lieutenant governor of Colorado. Tillemann-Dick's mother, Annette Lantos, home-schooled her daughter and Charity Sunshine's 10 siblings. A local paper dubbed the storied family -- some of the siblings' names: Zenith, Liberty, Mercina, Gloriana -- the Royal Tenenbaums of Denver.
"I have a bit of an unusual family, but we're fun," Tillemann-Dick said.
Tillemann-Dick's diagnosis in 2002 came shortly after she graduated from Regis University in Denver, Colorado, with a minor in music. A year later, as she studied at the conservatory at Johns Hopkins University, Tom Lantos told his old friend Condoleezza Rice, who was U.S. national security adviser at the time, about his granddaughter's illness.
Rice, a classical pianist, had an idea. She asked Tillemann-Dick if they could perform together. In 2006, Rice, then secretary of state, played Mozart and Verdi at the Kennedy Center with the 21-year-old singer. Political heavyweights including Kofi Annan, then secretary-general of the United Nations, applauded.
If it seems like a charmed life, it came with plenty of pain.
Lauded American composer Lori Laitman, Tillemann-Dick's longtime teacher and friend, visited her protegee in a hospital in Italy in 2008.
"I knew Charity was ill, but I worked with her for so long without really comprehending just how sick she really was," said Laitman. "When I walked into that room, there she was, sitting in her bed with tubes in her nose, so thin and worn out ... and writing a musical. Charity asked me, 'Will you listen to this?'"
From diagnosis until weeks before her transplant, Tillemann-Dick exhausted herself on international stages. Fearful that directors would replace her, she hid her illness by wearing heavier makeup to disguise sallow skin. She tucked a cassette-size medication pump in her skirt. She didn't let on when her eyesight became blotchy. She often felt nauseated, a side effect of her medication, but she held it together.
The singer appears to have approached recovery from her transplant surgery in the same manner she battled her illness -- she would sing, no matter how awful she felt.
At a point where most patients are barely speaking, Tillemann-Dick started retrained her voice by humming. As her body strengthened, her pipes were ready for jazz, then folk, and eventually she was singing show-tunes. Still connected with Washington, she's performed this summer at the Swiss and Hungarian embassies.
She sang "O Mio Babbino Caro" for those audiences, too.
The aria's line, "My love for which I suffer," carried, perhaps, a meaning stronger for her now.