Why should we be of service to others?
The Bible tells us we should serve others.
"He who is greatest among you shall be your servant. And whoever exalts himself will be humbled, and he who humbles himself will be exalted." (Matthew 23:11-12)
"Whoever desires to become great among you shall be your servant." (Mark 10:43)
"The King will say to those on His right hand, ‘Come, you blessed of My Father, inherit the kingdom prepared for you from the foundation of the world: for I was hungry and you gave Me food; I was thirsty and you gave Me drink; I was a stranger and you took Me in; I was naked and you clothed Me; I was sick and you visited Me; I was in prison and you came to Me.’Then the righteous will answer Him, saying, ‘Lord, when did we see You hungry and feed You, or thirsty and give You drink? When did we see You a stranger and take You in, or naked and clothe You? Or when did we see You sick, or in prison, and come to You?’ And the King will answer and say to them, ‘Assuredly, I say to you, inasmuch as you did it to one of the least of these My brethren, you did it to Me.’" (Matthew 25:34-40)
And in the end, this is what makes us truly happy.
"Real joy, which comes from loving to do good things without wanting to be repaid, is the reward that lasts forever. The Lord puts heaven and unending happiness into this kind of goodness." (Emanuel Swedenborg, New Jerusalem and its Heavenly Doctrine 156)
"Worship of the Lord consists in performing useful services." (Emanuel Swedenborg, Secrets of Heaven 7038)
"[The Lord] gives those who are performing useful functions a love for being useful, and also a reward for being useful, which is inner bliss; and this inner bliss is eternal happiness." (Emanuel Swedenborg, True Christianity 736:3)
"The only source of anyone's true happiness is doing something useful." (Emanuel Swedenborg, True Christianity 735:5)
"[Heavenly joy] is the delight found in doing something useful for ourselves or for others." (Emanuel Swedenborg, True Christianity 734:3)
"We are born for no purpose but to be useful to the community we live in and to our neighbor as long as we are alive in the world, and to serve at the Lord's good pleasure in the other world." (Emanuel Swedenborg, Secrets of Heaven 1103:2)
"Life holds no joy unless it is active. Angelic life consists in usefulness and acts of neighborly kindness." (Emanuel Swedenborg, Secrets of Heaven 454)