Joy becomes rebellious in environments that treat exhaustion like status.

In places where being visibly drained is a mark of commitment, enjoying yourself starts to read as a lack of seriousness. That is a strange arrangement, and choosing joy inside it becomes quietly defiant. You are refusing to accept that depletion is the price of being taken seriously, which threatens the arrangement more than complaining ever would.

Have a look at what earns approval where you spend your days, and whether tiredness is one of the currencies. If it is, you do not have to announce anything. Just leave on time, take the real break, and decline to compete on exhaustion, and notice who quietly follows.