Your job can be taken, your money can go; your health, your status, your reputation -- all of it is on loan. Seneca knew this, which is why he lands on this one uncomfortable truth in the very first letter he ever wrote to Lucilius: time is the only thing that actually belongs to you. And most of us spend it like we've got a surplus.

Think about how protective you are of other things. For example, you’d notice immediately if someone nicked a tenner from your wallet. But three hours disappears into your phone (in the form of doom scrolling) and you shrug it off or not notice the loss at all.

Seneca's point isn't that you should become some productivity robot who optimises every minute. Instead, he's saying: at least notice what you’re giving away and how precious a resource it is.