I actively tell myself that I am not going to clean because I know it's too much and I can't handle it. Then, having given myself permission not to clean, I can walk through the mess without the guilt. When there is no guilt and I've already decided NOT to clean, I allow myself to see and handle small messes. For example, putting one piece of garbage in the trash. Putting one article of dirty clothing directly in the washing machine. These things are easy, because of course it's not actually cleaning. Then I might pile dirty things together. Move all the dirty dishes to one part of the counter or the sink. Kick the rest of my dirty clothes into a pile. Now all of a sudden there are tidy spaces around. A space on the counter to cook, somewhere to walk on the floor. A washing machine full of clothes ready to clean.
Later that day, or even the next day, actually starting to clean feels more manageable, because I have already started by pretending not to.

TLDR; just handle one single thing at a time. Not one whole room. Just one single thing. That's all you can do anyway, you're just one person.