The aim is to determine the predictive effect of Satisfaction/Fun, boredom, the importance of Physical Education (PE) classes, and intention to engage in leisure-time physical activity (LTPA) on the level of physical activity (PA) in primary school children. This is a cross-sectional causal study. A total of 519 children from the states of Jalisco and Nuevo León participated, with an average age of 10.50 ± 0.94 years. Inclusion criteria included signed informed consent; children with any pathology were excluded. The analysis included descriptive statistics and multiple linear relationships. The results showed high levels (M > 4) of Satisfaction/Fun, importance and usefulness of PE classes, and intention to practice LTPA; moderate to low levels of PA and boredom. Significant differences (p = 0.001) were found in PA levels by gender and state and in the importance of PE classes by gender. Fun/Satisfaction and intention to engage in LTPA were the best predictors of PA with values of [beta] = 0.25; [beta] = 0.19; F (2,516); (p = 0.001); R[superscript 2] = 0.15. PE classes should include strategies that promote student satisfaction and fun and reintegrate the learning unit into the current curriculum framework.