My version of this is:
If wishes were horses, beggars would eat well.
Grandpa always said this about dreams but it applies to wishes just as well:
"If you're gonna dream, dream big, it don't cost any extra."
Also, about the word IF: "IF frogs had wings they wouldn't bump their butts on the ground so often"
-and; "IF the dog hadn't stopped to s***, he'd-a caught the rabbit."