Last May, when Winter Vinecki, 9, learned her father was diagnosed with a rare, aggressive form of prostate cancer, she knew what she would do. An active child growing up in Gaylord, Mich., she has a passion for triathlons -- she swims, bikes, and runs, and competed in her first one at age 5. Struck by how many kids in her school were overweight and out of shape, she had thought of putting together a team of like-minded friends and family (including her three brothers and mom) to race and raise money for kids' health. "But then my dad got sick," Winter says. "I decided the team should help find a cure for this cancer that was hurting my dad."

And so Team Winter was born. In just a few months, she has gathered runners and triathletes from all over the United States to join the team, which has raised more than $100,000 to benefit Athletes for a Cure and the Prostate Cancer Foundation. Her calendar is packed with upcoming events, including a 10 mile race on Dec. 6 for her 10th birthday. "I want to tell everyone about this disease," she says. "I think if we can raise enough money there can be a cure." And to meet that goal? "I just focus on crossing the finish line and getting there"

Katherine Stone, 39, skipped the chapter about postpartum illnesses in What to Expect When You're Expecting, but in hindsight, wishes she hadn't. "Had I been more educated, I might have spent the first year of my son's life in a different place." Instead, she found herself battling postpartum obsessive-compulsive disorder, one of a wide spectrum of illnesses that can occur around delivery and after giving birth. By the time of her son's first birthday in September 2002, Stone had been on medication and in therapy and had finally turned the corner.

But the experience kept haunting her. "It bothered me how isolated and alone I felt. There's no reason, in this day and age, for me not to know where to turn, not to know how common this is." So in 2004, the former Coca-Cola executive based in Fayetteville, Ga., put her marketing savvy to work and launched a blog called Postpartum Progress to give women a place to find comfort and answers. Now it's the most widely read blog on perinatal mood and anxiety disorders in the United States, with more than 3,000 readers weekly. It covers the latest research, support groups and treatment programs, personal stories, and the Surviving & Thriving Mothers Photo Album. "I really wanted to create something that refutes the myths, combats the fears, and reduces the stigma," says Stone, now a mother of two.

When Jane L. Delgado is not running the National Alliance for Hispanic Health (as she has for 23 years), brainstorming ways to improve services for the 100 million helped annually through its national members, hosting health fairs across the country, or updating Salud, the PhD's definitive book on Latina health, she's thinking about air. And water. And how to clean up some of the dirtiest cities in America to give urban kids a better future.

This is why she is outfitting young people with state-of-the-art mobile Eco-Pac pollution monitors in Brooklyn, N.Y.; Brownsville, Texas; Detroit; and Watsonville, Calif. These kids are taking part in her Health and Environment Action Network, launched in 2007. "Each area was picked because the pollutants there are very different," she says. The data, videos, and maps documenting the pollution will be posted at Health and the Environment Action Network and sent to the Environmental Protection Agency as an official first step in calling for national and local action. "Getting kids involved in health and the environment has been something that I have believed in a long time," Delgado, 55, says. "It's our world, it's our health. And their future."

For five years, Laura Ziskin tried to get diagnosed with breast cancer. She just knew something was wrong. But doctors, mammograms, and even an ultrasound declared the Pretty Woman and Spider-Man series producer cancer-free. Then one day in 2004 her breast looked different: It had a dent. When she showed it to her ultrasound radiologist, "the woman went white as a sheet," she recalls. A mastectomy, chemo, and radiation followed. Ziskin slowly allowed herself to believe she would survive. And then she got mad. "Why can we go to the moon and split the atom, but not solve cancer?" she wondered.

Every day more than 1,500 people in the United States die of cancer. For Ziskin, now 58, a way to fight back came when she produced the 2007 Academy Awards, which honored An Inconvenient Truth, the movie that catapulted "going green" into the zeitgeist. "I decided that I was going to make the Inconvenient Truth of cancer," she says. This Sept. 5, Stand Up to Cancer aired on the three major networks and raised more than $100 million for research and treatments. Says Ziskin, "I believe if one new drug comes out of this process, we will have been a success." And, she predicts, "that will happen."