Recess provides an opportunity to promote physical activity among schoolchildren. There is limited research on the effects of specific recess interventions, such as moveable equipment, physical structures, or painting playground, on motivational and affective-emotional variables. The study investigated the impact of a recess intervention based on children's play using their own self-made materials. The researchers examined how this intervention affected basic psychological needs (including novelty), motivational regulations, self-determination index (SDI), and mood states, such as fear, happiness, sadness, and anger in 219 schoolchildren from third to sixth grade. The multivariate analysis of variance and univariate analyses found a decrease in identified, introjected, and external regulations, amotivation, and fear and an increase in SDI by grade. Boys scored higher on autonomy, competence, external regulation, and anger while girls scored higher on happiness. SDI and novelty were predictors of happiness in boys while relatedness was the main predictor for girls. Relatedness negatively predicted anger in boys. SDI negatively predicted fear and sadness in both genders. These findings suggest that recess interventions should consider motivational and emotional differences by grade and gender to promote physical activity and well-being in schoolchildren.