The concept of the U-shaped curve has been a well-established fundamental principle in the realm of psychological science, especially in theories related to motivation. This research (N=330), aimed to empirically validate the prediction of a non-linear, U-shaped relationship between task difficulty and the adaptation of control. Grounded in Motivational Intensity Theory (MIT) and the expected value of control (EVC) framework, our hypothesis posited that an increase in task difficulty will be followed by an increase in control intensity, until a maximum tolerable level, after which it would decrease. To test this hypothesis, we conducted two experiments utilizing Stroop-like conflict tasks, systematically manipulating the number of distractors to modulate task difficulty. Control adaptation and subjective task difficulty was measured. The results uncovered a curvilinear relationship between perceived task difficulty and the adaptation of control. These findings provide empirical support for the theoretical accounts of MIT and EVC, emphasizing the nonlinear nature of the relationship between task difficulty and cognitive control.