This article presents a case example of an individual with current major depression engaging in a positive mental imagery intervention, specifically a computerized cognitive training paradigm involving repeated practice in generating positive imagery in response to ambiguous scenarios. The patient's reported experience of the intervention suggests the potential of the positive imagery intervention to “brighten” everyday life via promoting involuntary “flashes” of positive mental imagery in situations related to the scenarios, with associated beneficial effects on positive affect, future expectations, and behavior. Enhancing this aspect of the training–i.e., involuntary positive imagery in contexts where it is adaptive–may hold particular promise for reducing anhedonic symptoms of depression. Developing simple computerized interventions to increase the experience of positive mental imagery in everyday life could therefore provide a useful addition to the drive to improve treatment outcomes.