Make Hay While the Sun Shines
(take advantage of an opportunity to do something)
Come on, Jed. Don't be such a wet blanket! Come with us to the state fair.
I'd like to, but I'm swamped with work. Maybe next time.
That's what you're always saying, and next time never comes. You're young. Make hay while the sun shines. Trips like this one don't come around every day.
I'm really tempted, but I've got to finish this paperwork.
Meanwhile, life is passing you right by. You should take advantage of an opportunity to do something when it's available. Doesn't the fact that Mary Ann will be coming along tempt you?
Mary Ann is going?
Absolutely.
Well, maybe just this once I could take a break from working. OK. Count me in!
be swamped with = 〜で忙殺される