Endorphins are neurotransmitters released during exercise that significantly affect mood and motivation. They interact with the brain's opioid receptors, leading to feelings of happiness and reducing perceptions of pain, often referred to as the "runner's high." This natural mood boost can increase exercise motivation, making individuals more likely to engage in physical activity regularly. When consistent, these elevated endorphin levels can produce long-term improvements in mental well-being and resilience against stress.