To comfort the afflicted and afflict the comfortable. (Apparently originated by Finley Peter Dunne)
Sharing a drink called lonliness is better than drinking alone–Billy Joel (paraphrased)
A good man is hard to find. (traditional)
A hard man is good to find. (Mae West)
“Ask not what your country can do for you; ask what you can do for your country.” - JFK
The odds are good, but the goods are odd.
If you don’t work your program, your program won’t work.
(in regards to self-help programs such as AA)
Oh, almost forgot!
“I went home at 2 with a 10, woke up at 10 with a 2”
“I believe that it’s better to be looked over than it is to be overlooked.”
“It’s not the men in my life that count, it’s the life in my men.”
Maybe Elendil’s Heir was thinking of “Existential Blues” by Tom “T Bone” Stankus, a longtime staple of the Dr. Demento show? That line pops up in that song.
Oh, and I’ll add to the list:
“When the going gets tough, the tough gets going”
and
“You can take the X out of Ybut you can’t take the Y out of X” as in - “You can take the man out of Jersey, but you can’t take the Jersey out of the man.”
Broad generalization, I know, but heard in several different forms over the years:
Men use love to get sex, while women use sex to get love.
FYI, the term comes from the Greek letter chi, which we know better as X. Note the connection between the letter form and the meaning.
“Winners never quit, and quitters never win.”
“Love begets love, and vice-versa.” 
Dorothy Parker: “Too fucking busy, and vice versa.”
Here’s one I recall (from a forgotten source):
An old saying in the Soviet Union about the two major government news sources; Tass (which means “truth”) and Izvestia, (which means "news’):
“There is no truth in Izvestia and no news in Pravda”.
That that is, is. That that is not, is not. Is not that it? It is.
To quote Greg The Bunny:
Gil: “I never let sex get in the way when I’m out for blood.”
Susan: “That’s funny, it’s usually the other way around for me.”
:eek: