The garage is where things go to wait, and the waiting room is full. The cleanout is different from tidying: tidying rearranges the boxes; the cleanout opens them. Three piles — keep, pass on, throw away — and one rule: anything you have not touched in a year goes to the second or third pile without an appeal.
Work one wall at a time, and do not let the keep pile grow as the morning goes on. When the sorting is done, the room is already half empty. Then comes the part that makes it last: shelving on the walls, hooks for the ladder and the hose, and a floor you can sweep. Things on the floor multiply; things on shelves do not.
Finish with a marker and a roll of tape: label every box on the shelves in one line, because the label is what saves the next search. The weekend costs effort, but the payoff is the room itself — a place where the car fits, the tools are findable, and nothing waits for you to forget it.