Patrick Stephenson knew he needed to change how he was living, and he gave himself 30 days to do it.

His goal: de-clutter and de-stress.

"I didn't like my home," he said. "I felt suffocated by all the stuff that I had that I was just carrying around."

In January, he committed to a 30-day challenge that called for getting rid of one thing the first day, two things the second day and so on until by the end, a person would have unloaded nearly 500 possessions.

After 30 days, Stephenson, of Minneapolis, was a changed man.

"It's awesome. It's transformative," he said.

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Stephenson and many others are embracing the "30-day challenge" model to change aspects of their lives for personal growth and health reasons.

The trend's popularity can be seen in the hundreds of smartphone apps on the market that reference "30 days." While most of these kinds of challenges focus on exercise or nutrition goals, there are 30-day challenges for just about anything.

Looking to break out of your comfort zone? Try talking to a stranger every day for 30 days. Or if that's too scary, wear a different lipstick shade each day for 30 days. And if your self-esteem needs a boost, write positive things about yourself each night and repeat them the next morning for 30 days.

Other challenges involve taking a stab at doing something on the old bucket list — like writing a novel. There are challenges for learning to play musical instruments, and challenges to turn you into a better wife/husband/parent in 30 days flat. The hope, say enthusiasts, is that doing something with gusto for 30 days will create a habit.

The magic number

All this 30-day challenge talk began in earnest a few years ago when a Google engineer named Matt Cutts gave a popular TED Talk urging people to "try something new for 30 days."

He argued that 30 days was the right amount of time to form a good habit — such as biking to work — or eliminate a bad habit — eating foods with added sugar, for instance. However, studies show that it actually takes much longer — about 66 days — for a habit to stick.

Nonetheless, the 30-day idea caught on big time. Part of the allure, say those who've embraced the challenges, is that they seem manageable.

"You can do anything for a month," said Andrea Ahneman, a Twin Cities runner and blogger who has taken up exercise challenges that involved doing planks, squats and push-ups.

"It really does feel like a magic number," added Stephenson, who also helps organize "30 Days of Biking," an annual challenge in which people pledge to bike every day throughout April and record their experiences online.

More than 4,000 people had pledged to complete the 30 Days of Biking challenge. The act of pedaling every day for a month — no matter how far — and connecting to other people who are also doing it has turned recreational riders into daily riders, Stephenson said.

"We've seen a lot of stories like that. There was a lady in Nebraska. She started in 2011. She made a devotion to bike every day after that — every day of her life. She did 365 days of biking after that. She's still going."

Quick fix vs. lasting change

Despite their appeal to the masses, the 30-day approaches have their critics among those who study health and fitness programs.

"It's a mixed bag," said Lisa Ferguson-Stegall, director of the public health sciences program at Hamline University in St. Paul. "At best, it can motivate people to use it as a steppingstone. However, a lot of the challenges are limited in their scope."

Popular ones such as the ab challenge or the squat challenge tend to target only one muscle group.

"The idea that you can do these squat exercises for 30 days and have a bikini butt is really unrealistic," Ferguson-Stegall said. "And it's not going to do a lot for your overall health."

Those kinds of workouts, she argued, are no substitute for true, regular exercise that targets the heart as well as muscle strength, muscle mass and bone density.

To develop an exercise habit that continues beyond 30 days and thus results in lasting change, experts recommend doing an enjoyable activity at the same time every day in a comfortable environment.

Felicia Stoler is a nutritionist and exercise physiologist in New Jersey and a fellow with the American College of Sports Medicine who is familiar with the 30-day challenge trend. She said that while they can work in some instances, "ultimately, they are a fad exercise regimen program for most people."

Part of the reason people don't last beyond 30 days, she suggested, is because some challenges ask them to do something that is complicated or involves doing something they don't like to do. The food-related challenges can be particularly hard, she said.

"Some of these challenges involve crazy diets that they can't sustain because they have foods that people don't like, or that they can't make, or it just doesn't fit into their lifestyle," she said.

Allie Shah • 612-673-4488

@allieshah