Don’t be a macho idiot
No, you cannot empty your entire bookshelf into one giant box and carry it down three flights of stairs. And if you do manage it, that’s going to be you done for the day -- maybe for the next month. Professional movers can do this because they have spines of iron and the stamina of a sexually adventurous racehorse. If this does not describe you, pack smaller.
Hire a maid
The last thing you’re going to want to do after moving all your stuff is go back to your old place and scrub the evidence of a year’s solid partying off the walls for three hours, before handing the keys back. Hire a maid to come in while you’re moving your stuff to the new place, then come back to a squeaky clean apartment just in time to give your former landlord his keys back and get your security deposit returned in full.