"Order my steps in your word, dear Lord," their voices surge, repeating one of contemporary gospel's popular hymns. "Guide my feet in your word. Show me how to walk in your word."
Johnson smiles down at the tiny $20 plastic monitor clipped to her skirt. "31,995," the pedometer reads, documenting the number of steps she's taken in a week. Nearly 13 miles.
Johnson, 48, is one of 150,000 people in Colorado in a program determining whether modest physical effort will prevent weight gain — now recognized as America's second-leading cause of preventable death behind smoking.
On Thursday, the pedometer program expands nationally. Its founders hope to have 1 million people signed up for "America on the Move." They will begin walking at least 2,000 additional steps a day, about a mile, to burn 100 calories.
And they'll trim another 100 calories a day from their diets.
Johnson, who directs health programs for the Metro Denver Black Church Initiative, started wearing a pedometer more than a year ago. She not only stopped gaining weight, but when she increased her daily walking to about 10,000 steps, she lost more than a dozen pounds and cut back her hypertension medicine.
Now she considers the paths of health and redemption to be intertwined. "It's the same as the gospel," she says. "God doesn't care where you are when you start. You will reap the reward."
Mixing religion with science makes most researchers acutely uncomfortable. But it's a message that resonates in Johnson's community. She's distributed 1,600 pedometers to extra-large parishioners in 32 black churches in Denver.
Colorado is America's leanest state, but even its obesity rate has more than doubled since 1990 to 14.9 percent.
"I looked in the mirror and I didn't see the girl I used to be," Johnson said. "I started walking and things started to shift around. I've dropped a couple of sizes."
Can such a modest plan lasso a lumbering nation?
Results from the Colorado walking effort are being submitted to scientific journals.
Over 16 weeks, 85 percent of all participants raised their activity level by a total of 2,000-2,500 steps a day, the researchers say. But it will take a year to see if they stabilize, or even lose pounds, and it will take several years to see if the weight loss is sustained.
Like the Colorado experiment, only a fraction of America on the Move participants nationwide will be enrolled in a supervised study. Others can follow the same recommendations independently by registering on the program's Web site.
James Hill, the program's co-founder, says it's the first effort at systematically studying "how you stop obesity from getting worse."
"Our idea is dirt simple," says Hill, director of the Center for Human Nutrition at the University of Colorado Health Sciences Center. "If it doesn't work, we're in big trouble as a nation."
Statistics suggest we already are.
Obesity-related ailments cost $117 billion to treat, and contribute to 300,000 deaths annually, according to federal estimates.
Two out of three adult Americans are overweight, the government says, and they're gaining nearly 2 pounds every year. A quarter of them get virtually no exercise.
For African-Americans, the problem of expanding waistlines is grimmer still; 60 percent of black men and 77 percent of black women are too heavy, doubling their already-elevated risk of diabetes and other diseases.
Regardless of who you are, probably 100 genes control your metabolism, the complex system that converts food into fuel for cells, burning some and storing the rest for later.
It's a system that emerged with the rise of mammals 65 million years ago and evolved in modern humans tens of thousands of years ago.
Its message to our upright-walking ancestors was to eat whenever they found food. They foraged for every precious calorie.
Now food always is available. And it's not roots, berries and bugs. It's chips and dip. Burgers and fries. Pizza and beer.
"Our bodies have never had to develop a system to avoid weight gain," said Hill, who walks 11,000 steps a day, about 4½ miles.
On the Move critics say willpower naturally shrivels when we are surrounded by enticing foods and our genes are commanding us to eat.
"There is a basic biological framework that regulates weight," said geneticist Jeffery Friedman of Rockefeller University.
Friedman believes the solution lies in manipulating hormones and other chemical cues controlling appetite.
However, early experiments on this have had mixed results.
Hill says most heavy people don't have an obvious genetic disorder.
For years, Lucille Johnson simply ate more than she burned off.
A single mother of two, she confused being busy with being physically active. Now she rises at 5 a.m. to walk before her daughters go to school.
Johnson trimmed 100 calories by limiting fatty snacks like cookies and cheese. She is reformulating her favorite recipes, eliminating lard, ham hocks and bacon drippings.
Her daughters, a high school freshman and a sixth-grader, are tall and willowy. She gave both girls step-counters in hopes they will regularly outwalk their mother and remain thin.
"That's my prayer," she says.