Background: Shy children often avoid interacting with their peers, which can restrict their participation in physical activities and impact their physical fitness. Therefore, it is essential to offer specific support and strategies to assist these children in increasing their involvement and enhancing their physical fitness. Objectives: This study aimed to investigate how physical education, utilizing a humanistic approach, impacts the physical fitness and daily physical activity behavior of shy children. Methods: In order to achieve this, a quasi-experimental field study was planned with pre- and post-tests including a control group. Participants were 9 to 10-year-old elementary school girls from Tehran, selected based on the Chick-Briggs Shyness Scale Physical fitness was measured using tests for cardiorespiratory endurance, agility, muscular endurance, muscular strength, and flexibility. The physical Activity Questionnaire for Children (PAQ-C) was utilized in assessing children's attitude towards physical activity. The experimental group (n = 15) received a physical education course with a humanistic approach using the teaching physical and social responsibility (TPSR) model, while the control group (n = 15) maintained their usual daily routines. Results: The experimental group showed significant improvements in physical activity levels, muscular endurance, and flexibility compared to the control group. A humanistic, game-based educational approach using the TPSR model can effectively improve certain components of physical fitness and promote a positive attitude towards physical activity in shy children. Conclusions: This approach can help teachers and coaches better understand and assist this group of children in overcoming the negative relationship between shyness, sports participation, and physical fitness.