National Institute for Fitness and Sport Non-profit organization committed to enhancing human health, physical fitness and athletic performance through research, education and service. http://www.nifs.org

National Strength and Conditioning Association Non-profit association dedicated to facilitating the exchange of ideas in strength development as it relates to the improvement of athletic performance and fitness. http://www.nsca-lift.org/menu.asp

IHRSA International Health, Racquet and Sportsclub Association: Organization that promotes fitness through education and sport club membership. http://www.IHRSA.org/

The Fitness League National network of locally based exercise classes, suitable for all ages and abilities, available in over 300 venues across the UK. http://www.thefitnessleague.com/

Association of Women's Fitness Resource site on women's fitness and health, with a special focus on preventing home gym training injuries. http://www.association-of-womens-fitness.org

National Association for Health and Fitness A not-for-profit organization that exists to improve the quality of life of every individual in the United States through the promotion of physical fitness and healthy lifestyles and by fostering and supporting Councils for physical activity, health and sports. http://www.physicalfitness.org/

American College of Sports Medicine Promotes fitness, health and quality of life through research, education and practical applications of sports medicine. http://www.acsm.org

IDEA Supports the world's leading health and fitness professionals with credible information, education, career development and leadership. http://www.ideafit.com

National Center on Physical Activity and Disability NCPAD encourages persons with disabilities to participate in regular physical activity to promote healthy lifestyles and prevent secondary conditions. http://www.ncpad.org/

International Yoga Federation Lists the national and continental yoga organizations. http://fiy.yoganet.org

American Society of Exercise Physiologists Certification (EPC), undergraduate academic accreditation, electronic research (JEPonline) and publications (PEPonline), licensure through state affiliates. http://www.asep.org

Healthy Child Initiative Foundation Researches and promotes physical activity and nutrition in children. Launched by Canadian Olympic rower, Silken Laumann. http://www.silkenlaumann.com/childhealth.htm

Moms In Motion Programs provide fitness training for women and raise money for local charities. http://www.momsinmotion.com

Exercise Friends Search for an exercise partner. Friends can help to motivate. http://exercisefriends.com