How do I keep going when everyone at work leans on me?

You are good at making work better for other people. That is a real gift, and it is also why everyone comes to you. The very thing you are known for has turned you into the place where everyone sets down their load. Burnout here is not a sign you are failing. It is a sign you have been giving without refilling. You cannot pour from an empty cup, and no one has been pouring back into yours. That has to change, and it starts with you saying it out loud instead of quietly carrying more. Pick one thing this week to hand back. Tell one person you cannot be their only support, and point them somewhere else. You are allowed to build a program that protects you too. The people who lean on you will survive you having limits. You might even teach them to stand on their own.