Y is for my favorite Yiddish proverb

Not long into my widowhood I discovered a Yiddish proverb that translates to "When one must, one can."  I resolved to make that my motto as I trudged through life alone.  Know what?  It's a wise and somehow comforting saying and I've done my best to live by it because...what choice does one have?

If you have a favorite proverb, list it in the Comments section.