Time
"The Angel of Death sits on every word." - JBP
Time is the riches best-kept secret. It is something you can never get back. You can make more money, you can drink more water, you can eat more food, yet you can't get your time back.
Imagine standing at a traffic light, and as you walk across the road, you trip over a bit of concrete which is slightly higher than the rest. As you fall face first onto the concrete, an unaware driver rips down the road and squishes your head by accident. Your life is now gone; there is no family, there is no money, there is no joy or suffering, you are simply no longer here.
Do what you need to do with the time you have. It's a trap to think it’s never ending. The hourglass will run out, and hopefully not simply shatter. Spend your time with your family, take care of them. Start a new hobby or business. Build something because you want to. Don't spend your time doing what evil forces want you to, because you never know, today may truly be your last day.