A stroller folds down small, but only if you clear out the basket first and use the actual fold latch instead of forcing it. Do that and it becomes one of the easiest things you own to load.
Pro tip: Snap the fold latch closed before you even start loading; a stroller that pops open mid-carry is a common way movers scratch other furniture.
Watch out: Do not fold a stroller with a child or pet inside it, and keep fingers clear of the auto-lock hinge, which snaps shut with real force.