Maybe I'm just old, but what about
Gloria Gaynor I Will Survive? That's classic.
I also love the irony in
Elton John's I Want Love\
And I happen to be an old-fashioned musical theatre geek, so I also have to go with
It's A Fine Life from Oliver!
Finally, I sent
this Eric Idle YouTube to my son who just lost his job last week. It just cheered me up, but then again, I was raised Catholic.
Note that all of the songs except for I Shall Survive are included for their irony and their cautionary tales about how our minds can delude us into thinking all's well when it actually isn't.