Me: Whoa! It's very late, we should have started getting ready for bed 20 mins ago.
Sempi: 20 minutes isn't that much. If you think about it, it is only 4 time 5 minutes.
Sempi: And if you think about it, 5 minutes is just 5 times 1 minute.
Sempi: And if you really think about it, 1 minute isn't that long.
That's the spirit. I should remind him of this conversation when he starts doing planks.