Clannad, Rince Philib a’Choeil: Clannad Rince Philib a'Cheoil - YouTube
Our House - Crosby Stills Nash & Young
I’ve liked this song since the 70s and just found out that Graham Nash wrote the song about the time he was living with Joni Mitchell
All You Need Is Love - Beatles
Shown here from the animated feature film Yellow Submarine: https://vimeo.com/267720148
Good thread.
This one, by Paul Simon, is like swallowing a happy pill. I especially love the gospel-ness of it:
Gone At Last
mmm
Groovin’ (On a Sunday Afternoon)
Oly, the monotone in that version of The Happy Wanderer is just one issue; another is that the singer can’t stay in tune and keeps changing key!
Here’s a cute Muppets version, but don’t listen if you don’t want to get earwormed 
Crafter man, one of my faves
30000 Pounds of Bananas (Harry Chapin)–I’m not going to say why I think it’s a happy song: https://www.youtube.com/watch?v=OGldNpngDws
I’m not drinking that even if trapped On a Coconut Island. (Louis Armstrong with The Polynesians)
Actually, now I’m curious as to what it tastes like.
I love it! Thanks for sharing!
You’re such a silly woman. 
Sly and the Family Stone, “You Can Make It If You Try”
Smile, Darn Ya, Smile! (1931) Foxy & Roxy in a Warner Brothers cartoon here: Smile, Darn Ya, Smile! (1931) - YouTube
George Harrison - What Is Life
A classic, happy song. McFerrin lived in San Francisco in the late 1980s and his kids played in the same soccer league as mine did. So I’ve seen him on the soccer fields, but I never went up to him to say hello.
Great song.
In every life we have some trouble
But when you worry you make it double
Don’t worry, be happy