the key to happiness is not comfort, but discomfort
The longest running study on happiness:
Harvard's 84 year old Study of Adult Development.
Here are 7 lessons from the study to help you live a happier life:
“human beings need three basic things in order to be content: they need to feel competent at what they do; they need to feel authentic in their lives; and they need to feel connected to others. These values are considered "intrinsic" to human happiness and far outweigh "extrinsic" values such as beauty, money and status.”