Here is an equation worth remembering: Five dollars earned minus seven dollars spent = Unhappy Life." (Life Hacks, p.51)

[Credit is a system whereby] a person who can't pay, gets another person who can't pay, to guarantee that he can pay.

Money never prevented anyone from being happy or unhappy

I don't have a wallet. I carry my driver's license and a couple of credit cards in my phone. That, and a money clip.

I see very little other sources of financial catastrophe than credit-card debt,

Credit card debt is almost always bad. At the very least, make sure that the amount of credit card debt you have is less this year than last.