Self-control is a key skill that has important implications for life success. Parallel research programs in psychology, economics, and most recently neuroeconomics have identified important correlates and outcomes of self-control. Among those are for example educational achievements, financial stability, and health. However, the cognitive mechanisms underlying self-control remain elusive. The influence of situational modulators of self-control capacity such as stress has been recognized, but behavioral observations show that the impact of such modulators varies widely between individuals. In order to better understand inter-individual differences in reactions to self-control challenges and the impact of situational modulators on the effective use of self-control, I investigated it at the neural level. Combining behavioral and neural levels of analysis may allow us to better detect and understand changes in cognitive mechanisms that explain when and why some individuals fail in using self-control when experiencing such states. This thesis investigates the neural mechanisms underlying self-control in goal-directed choice using dietary self-control as a model behavior. In goaldirected choice, options can be flexibly evaluated based on the current state of the environment and current goals. That flexibility and generalizability allows agents to make optimal decisions in novel or variable contexts. One specific mechanism, a circuit involving the dorsolateral (dlPFC) and ventromedial prefrontal cortex (vmPFC) has been suggested to provide information about a goal while evaluating choice options and thereby bias choices in favor of self-control. The current work provides evidence in line with the notion that the dlPFC might introduce or stabilize a bias favoring a current self-control goal. Applying transcranial direct current stimulation (tDCS) showed that impeding the neural processing in dlPFC decreased the effective use of self-control in service of following a health goal. Conversely, facilitating information processing and propagation in the same area interacted with existing strategies to restrain dietary behavior and increased self-control in those individuals that were regularly applying such strategies. Taken together, this suggests that the dlPFC is causally involved in goal-directed self-control decisions.