Don’t save all your packing for moving for the last day! Be packing non-essential items well in advance. Packing to move gets more and more tiresome over a period of time, so jump start the packing endeavor as much as possible.
Basically, just take the time to think about what you’re boxing up and then use a lot of common sense packing it. When packing for a move, heavier things like books and canned goods should be packed in smaller boxes, and lighter things in progressively larger boxes. This way smaller and larger boxes will all weigh about the same and none will be too heavy for one person to handle. Small boxes can be fully packed with books and end up only weighing 50 lbs. Larger boxes should be packed with lighter things and should not be packed to exceed 50 lbs.