Our limbic brain, a kind of "affective" brain, functions on a "pleasure/pleasure" basis. It's responsible for attracting us to interesting, pleasant and not too complex things, and for pushing us to avoid unpleasant and difficult things. It thus influences our reptilian brain (that of our instincts and fundamental needs such as feeding, reproduction...), as well as our neocortex (the logical brain we use for learning).
Don't let it take over your study: avoid putting off too many subjects that are considered harder! Be careful, however, not to schedule unpleasant tasks for too long either, as this could lead to "fed-up" effects !
