Sin is a sickness in man's soul. When the bible calls us to live according to the will of God the bible calls us to live a life of spiritual and emotional health.
Often the human nature is such that we would rather be right than happy. It is easy to dismiss this as untrue.
The longer we think about it though the more often we could see how we could be or could have been happy in a situation if we were willing do give up on being seen as right in this or that.
The condition of pride eats at the soul. Sin is a disease that makes us unhappy.
We always wish to equate living as we please with happiness. But more often than not when we live as we please we are not happy.