2. Salt Lake City: Our cancer-survival capital

Why it won: Low cancer rates, along with the best cancer-survival rates among our 100 cities

Happiness hub: The Japanese-style healing garden at Huntsman Cancer institute

Cancer must hate Salt Lake. Thanks to the influence of the Mormons, people in this city are both clean living and much younger than in other places in the United States. (Large families lower the median age to 30.9 years versus the national average of 37.) That may be one reason Salt Lake City has one of the lowest rates of cancer per 100,000 people in the country. And for those who do get sick, the capital of Utah ranks No. 1 in cancer survival.

That makes perfect sense to Anna Beck, MD, medical director of supportive oncology and survivorship at Huntsman Cancer Institute. "The most obvious reason is that the predominant religion doesn't endorse drinking or smoking," she says, "so that cuts down on cancer incidence. And when people do get sick, it often means they were healthier in the first place, so their chances of recovery are also better."

In addition, outdoorsy residents tend to keep their weight in healthy ranges, which also lowers cancer risk.

The area's strong family and social supports are also key. Dr. Beck, who was diagnosed with breast cancer in 2007, knows that firsthand: "I'm luck. I had a thousand patients as role models, and they pulled me through."

Takeaway: Watch your BMI. With fewer people smoking, Dr. Beck says, a greater proportion of cancers are caused by obesity and being overweight. One report predicts that if Americans could reduce their BMIs by 5%, we could actually avoid 530,000 cases of cancer by 2030. (Consider this better BMI diet.)