This review summarizes recent findings regarding the status of physical activity and introduces effective methods of intervention. Data from our serial cross-sectional study between 2003 and 2012 suggested that the decline in step counts over the last decade is mainly related to a reduction in non-exercise activity associated with the increased use of cell phones or computers and with playing video games. We then examined the effects of lifestyle interventions using an activity monitor with computerized game functions or an activity monitor and Twitter on physical activity and body composition. These findings suggested that lifestyle interventions using both of these strategies increases daily physical activity and reduces body fat more effectively than using an activity monitor alone. In addition, changes in physical activity and in body fat were significantly correlated. We also applied a randomized intervention to examine an effective method of increasing physical activity levels among college physical education students using a pedometer. We found that using a pedometer and inducing friendly competition or encouragement from peers increased step counts more effectively during soccer classes. These findings therefore have important implications for ensuring compliance with the Physical Activity Reference for Health Promotion 2013 and Active Guide.