Yup. Been there. I attempted to replace mine with one of those electric ones. Says it cuts down on that sulfur smell for us well peeps. I do treat my system with a little bleach now and then too. Cleaned out the hole and got ready. Had a 1/2' drive on that baby with a pipe on the end. My dad (75) holding onto the water heater and still never broke loose. Kept moving the water heater and then broke the ratchet. So the new rod still sits there waiting for the next attempt. Afraid I will just rip the top of the water heater off. Really hate to put an impact on itTimely topic... I replaced the anode rod in my water heater today. Shoulda been done many years ago. There was literally nothing connected to the cap.
State (AO Smith) buries the access to the rod under 2-3" of solid foam. What a pain in the ass to get it cleaned through a small port out so no debris falls into the tank.
If you haven't replaced yours in the past couple of years, get on it.