How do I handle being on call all the time?

You keep the whole thing running, and the reward for doing it well is that no one notices. Meanwhile the pager never truly sleeps and neither, fully, do you. That wears on a person. The tiredness you feel is not a character flaw. It is the honest weight of always-on work. Part of what drains you is that invisibility and pressure feed each other. You carry the load and get none of the credit, so it starts to feel thankless. But steady systems are not luck. They are you, quietly doing your job well, over and over. That is worth respecting even when others forget to. Protect one real boundary this week. Pick a window where you are genuinely off, and hand the watch to someone else or let it wait. The systems can survive an hour without you. You need to prove that to yourself, so the always-on stops living in your body too.