This randomized controlled trial aims to evaluate the effect of a structured self-affirmation intervention on pain, depression, anxiety, and stress levels in patients undergoing mastectomy. The study will be conducted in two parallel groups, with the intervention group listening to an audio recording of positive self-affirmation statements. Primary outcomes will be assessed using the Visual Analog Scale and the Depression Anxiety Stress Scale (DASS-21). The goal is to provide evidence-based strategies to reduce psychosocial burden after mastectomy.