As a nation, our civic muscles -- and waistlines-- have become flabby from lack of exercise.

Over the last 30 years, community participation has dropped by 40 percent, according to "Bowling Alone: The Collapse and Revival of American Community" by Robert Putnam.

However, many Web sites that promote healthy lifestyles are depending on encouraging and active communities on the World Wide Web.

One such site is Livestrong.com, the newest addition to the foundation of seven-time Tour de France winner Lance Armstrong.

The site describes itself as the "definitive daily health, fitness, and lifestyle destination," for people of all ages with varying health problems and questions.

Joe Perez, an executive vice president, said that the makers of the site wanted a place where real people could engage with others on issues such as weight loss, managing diabetes and getting more sleep.

A survey conducted by Livestrong found that 86 percent of Americans have thought about making lifestyle changes to improve their overall health. Less than half -- 46 percent -- succeeded.

"We found that 'lack of motivation' was the primary roadblock in terms of making lifestyle changes to lead a healthier lifestyle," said Perez.

Perez said that although you need to be motivated and willing to make changes, you also need the right support system.

"Whether that support system is one person or your family, having support will ensure success," said Perez. "We feel Livestrong.com is a daily destination designed to provide motivation and support through our tools, content and community it offers."

The site also offers scientific health articles, an online food tracker, calorie counter and advice on issues such as dry scalp, neck pains, and balancing your family and career, and challenges, or dares, for members who "dare to change their lives."

Members can communicate with fellow participants to complete dares such as quitting smoking, getting more sleep, losing weight, exercising regularly and spending time with family.

They can also ask questions directly to professional trainers and other experts.

Perez said, "We envision the new site as ... a new online destination designed to inspire people to change their lives, help themselves, and help others."

Challenges For Every Runner

Nike Plus also offers motivating tools and a community for runners.

Nike partnered with Apple to create a program that uses an iPod nano or a wristband and shoe sensor to track and record personal workout information onto the Web.

The program is designed to be used by both dedicated marathon runners and daily joggers to visualize their runs, track goals and challenge other members to run longer, faster or more often.

Forums and discussion panels match up similar runners in the same city to exchange tips and create relationships with people who have similar interests and goals.

One forum showcases members Nike+ experiences. Many had positive posts and said how important the community was to their success.

"And today, after running for about 8 months, I reached a new milestone: 1,000 miles! Thanks to all of you for helping me improve and getting better, and I feel that this is just the beginning," one poster said.

Online Personal Trainers

Other Web sites offer smaller, intimate communities of online personal trainers for those who thrive off of direct attention and interaction with a few people.

Plus One Active offers a couple programs consisting of a self-driven program with customized workouts or a certified online personal trainer, according to About.com.

Hannah Harris, 21, a senior at the University of Wisconsin-Madison, has used a personal trainer and appreciated the motivation it gave her.

"They helped me stay dedicated to my goal and made the experience much more enjoyable," Harris said. "Plus, having that kind of support network is definitely a key foundation in building and maintaining a healthy lifestyle."