Why does He have to be happy ??
He was amongst carnal sinful flesh when on earth.
He was not an ogre or doleful...he was probably serious but not at all unapproachable in the first three gospels He says
Luk 18:16 But Jesus called them unto him, and said,
Suffer little children to come unto me, and forbid them not: for of such is the kingdom of God.
Little children are pretty receptive to moods so I suspect he was comforted by them and what they represented.
He was pleased when the centurian and the woman from canan showed more faith than those in Israel had
(Mat 8:10) When Jesus heard it,
he marveled, and said to them that followed, Verily I say unto you, I have not found so great faith, no, not in Israel.
When the woman from canan with the sick daughter persisted despite being strongle reproached by jesus
(Mat 15:28) Then Jesus answered and said unto her, O woman, great is thy faith: be it unto thee even as thou wilt. And her daughter was made whole from that very hour.
I also think that He was pleased when he quoted Isahiah 61:1 and part of 2
(Luk 4:18)
The Spirit of the Lord is upon me, because he hath anointed me to preach the gospel to the poor; he hath sent me to heal the brokenhearted, to preach deliverance to the captives, and recovering of sight to the blind, to set at liberty them that are bruised,(Luk 4:19)
To preach the acceptable year of the Lord.
(Luk 4:21) And he began to say unto them,
This day is this Scripture fulfilled in your ears.(Luk 4:22) And all bare him witness, and
wondered at the gracious words which proceeded out of his mouth. And they said, Is not this Joseph's son?
Most of all I think He was truly the happiest when He prayed to His Father.beloved