How do I keep up with cleaning when I'm exhausted?

You have proven you can keep things clean. The problem now is not knowing how, it is doing it when you have nothing left. Exhaustion is real, and willpower alone will not beat it. That is not a character flaw. It is just what tired bodies do. So stop relying on motivation and lean on habit instead. The cleaning you do without deciding is the cleaning that survives a hard day. Pick the one or two things that matter most and make them automatic, tied to something you already do, so they happen even when your mind is empty. Tonight, choose a single task and a fixed moment for it, like wiping the counter right after you eat. Do only that, and let the rest go. One reliable habit done tired beats a perfect plan you cannot keep. Build from there, slowly.