Quantitative and qualitative physical activity variables such as moderate to vigorous physical activity (MVPA) and motor coordination are likely to positively predict attention. No studies have yet investigated these coexisting effects or identified which are the most important among them in predicting attention. 324 children from two primary schools participated in 5 measurement times over 3 academic years. MVPA and sedentary time (ST) were measured by accelerometry. Motor skills were assessed with a shuttle run test, a standing broad jump and a plate tapping test. Aerobic capacity was measured with the PREFIT 20 m shuttle run test. Attentional capacities were measured with a computer-based Flanker Task: Reaction Times (RT) for sustained attention and inhibition were collected for each child. Two conditional inference trees and random forests were used to analyse the data. MVPA, ST, motor skills, grade, sex, and body mass index were included in the analysis as possible predictive variables of the two attentional variables. RT for sustained attention was predicted by grade, then by the shuttle run test and plate tapping test performances. RT for inhibition was predicted by the plate tapping test, then by shuttle run performances, grade and the standing broad jump performance. These findings indicate that attentional improvements may be due more to neural stimulation than to the benefits of cardiovascular exercise. No effect of ST was apparent. The data mining approach highlights the importance of gross and fine motor skills according to age in the prediction of sustained attention compared to inhibition.