I believe the secret to being happy is to walk in love and walking in love is impossible unless we allow the Holy Spirit to tenderize our hearts. As God says in Ezekiel 11:19, it is not His will for us to be hard hearted. Much of our sadness, depression and heaviness is linked to our behavior towards other people. Galatians 6:7 says that whatever we sow we will reap i.e. If we sow words or actions that sadden others we will reap sadness. We need to therefore learn how to walk in love with a heart that is open to God and sensitive to the needs of others.