sunny side, n. — Green’s Dictionary of Slang

sunny side n.

[the sunny side of the street]

the good, easy, materially satisfying life.

2003

Spectator Seattle University n.p.: The balance of the songwriting in Story After Story needs improvement. Hest’s songs don’t show any glimpse of the sunny side of life.

In phrases

on the sunny side of (adj.)

used to denote an age that is younger than a stated date.

1889		Music Hall & Theatre Rev. 16 Feb. 5/1: Anyone would take him to be on the sunny side of forty, instead of within a year of the half-century.
1897		T.J. Henry Claude Garton 243: Dr. Bradford was still a young man, on the sunny side of forty.