"That's Life" is a popular song written by Dean Kay and Kelly Gordon and first recorded by Marion Montgomery https://www.youtube.com/watch?v=qaSUXRSxrDU.
The most famous version is by Frank Sinatra, released on his 1966 album of the same name. Both the album and the song proved major successes for Sinatra.

LYRICS

Lyrics

Don't let it get you, don't let it get you down
'cause this fine old world, keeps on spinning around

That's life, that's what people say
You're riding high in April,
Shot down in May
But I know I'm gonna change that tune,
When I'm back on top, back on top in June

I said, that's life, and as funny as it may seem
Some people get their kicks,
Just a - Stompin' on a dream
But I don't let it, I don't let it get me down,
'Cause this fine old world it keeps spinnin' around

I've been a puppet, a pauper, a pirate,
A poet, a pawn and a king
I've been up and down and over and out
And I know one thing:
Each time I find myself flat on my face,
I pick myself up and get, back in the race

That's life, and I can't deny it,
I thought of quitting, baby
But my heart just ain't gonna buy it
And if I didn't think it was worth one single try,
I'd jump right on a big bird and then I'd fly

I've been a puppet, a pauper, a pirate,
A poet, a pawn and a king
I've been up and down and over and out
And I know one thing:
Each time I find myself layin' flat on my face,
I just pick myself up and get back in the race

That's life, that's life
And I can't deny it
Many times I thought of cuttin' out but my heart won't buy it
But if there's nothing shakin' come here this July
I'm gonna roll, I'm gonna roll, I'm gonna roll myself up in a big ball and die

Oh you can't deny it,
Now wait a minute, listen to me,
I said now don't let'em get you down,
Oh no, uh-uh, oh no, I said don't let'em get you down
Mmmm mmm mmm mmm
That's Life