Get the right boxes for your stuff so you don't have to lug around heavy stuff in big boxes and light stuff in small ones.
The suggestion is that bigger boxes should be for the lighter items that don't really gain weight until there's a lot in place, like sheets. If you've got a big box full of sheets, it's going to feel like a big box full of sheets. If you've got a big box full of plates, it's going to feel like you're carrying a car. One is easy, one is not, so make sure to pack things into the boxes that make the most sense.