Chinuch Horaah of the Day:
[In response to a woman’s question about her younger brother, who preferred to play rather than to learn, especially regarding limmudei chol.] It is quite common and normal for children to prefer games over learning, even when they are older than your brother. Hence, there is no need to be alarmed by this, although there is certainly a need to influence him be’darkei noam (in ways of pleasantness). The main thing is to utilize competition and comparison with his peers who are more studious. It is also worthwhile to minimize the hours that he learns limmudei chol, if it is not possible to eliminate this study entirely. This is because it is possible that this [reluctance] is a sign that he doesn’t want to pursue limmudei chol, even if at the moment he doesn’t understand the deeper reason behind this, and [eliminating limmudei chol] will automatically have a positive effect on his diligence in limmudei kodesh.
(Igros Kodesh, vol. 10, p. 293)