The difference between money and time.
Another gem from Seth Godin that made a big impact on me. Often people talk about money and time being the same thing. They are definitely related, but there is a key difference. Money not spent is money saved. Money can be put away, invested, saved for a rainy day. Time on the other hand, is much more valuable because the time we have is never going to be had again. Either you’re spending your time, or wasting it.