It is difficult to remember or memorize such a statement. Don’t you have a short, simple one?
I don't think it's possible. The sentence is as long as it is because of the number of semantic elements in it, and the precise nuance the author wants.
"We have to get up" - This can't be shortened much. "We must arise", I guess, but that's not natural.
"when"
"we would rather keep sleeping" - "we want to sleep".
"We must arise when we want to sleep." Shorter but it loses the meaning, which defeats the purpose of bothering to make a sentence.
How about "Waking up is hard to do"?