Going through the lecture notes, I found particular interest in the section of performance - mainly because I'm big on participating in various endurance events and the topic of motivation is one that typically comes up when talking with other participants, as well as a pushing internal force.
If anyone has participated in a sporting event knows the feeling of nervousness before the initial beginning - the "butterflies", followed by an extreme focus in which nothing matters but that moment in time. This arousal/performance relationship is known as "Yerkes-Dodson Law" which states, "as stimulation or arousal increases, performance increases, levels off, then declines." This increased arousal allows an individual to reach a point of peak performance, but if the arousal increases past that performance begins to suffer. As students, a very real application of this idea is apparent during finals - anxiety of an exam pushes you to study and remember the information but if that anxiety reaches a certain point it impairs your ability to concentrate on the material.