When Jesus was asked by a scholar, "Teacher, what is the greatest commandment?" He answered:

“You shall love the Lord, your God, with all your heart, with all your soul, and with all your mind.  This is the greatest and the first commandment. 

The second is like it: You shall love your neighbor as yourself”
(Matthew 22:37-39).

The only way to find true happiness in this world and the next is to follow these words of Jesus.