Patients with mental disorders often struggle to generate positive emotions, a critical deficit as positive emotions can cause cascading effects leading to well-being. Here, we focus on a specific form of positive emotion, compassion that arises as an affiliative response to other people. The cultivation of compassion has a long tradition in Eastern philosophy and, over the last years, in Western psychology. Recent evidence now shows specific mental training-related increases in compassion, going along with structural changes in the neural networks associated with positive emotions and emotion regulation. Exploiting the remarkable plasticity of the capacity to generate compassion appears to be a promising way to improve psychotherapeutic interventions, particularly when a focus on excessive negative affect reaches its limit.