Health and happiness influence each other. However, the relationship is quite complex, as a healthy person may be unhappy, and a seriously ill patient may experience happiness. Physical and mental health, and illness-related variables impact upon happiness, though it may be more pronounced by mental illnesses. Positive emotions, resilience, sex and intimacy, and social connectedness are usually associated with happiness, whereas stress, worry, pain, and depression are not. Happier people probably live longer, and there is excess mortality associated with unhappiness; however, many confounding variables exist. Interestingly, in recent years, biological substrates for happiness have been suggested. Genetics, neurotransmitters, specific areas of the brain, and biomarkers have been identified as being associated with the states of happiness. Achieving and maintaining happiness through health appears to have simple messages of being physically active, maintaining good health, preventing and managing illnesses well, having positive emotions, learning to be resilient against stress, and being generous and spiritual. Studies on health and happiness are building up in recent years, providing more insights into their interrelation. Happiness is being used as an outcome measure in clinical interventional trials and other health research, and there is an enhanced scope for its use in common clinical practice