This is actually a really simple trick you can do (if you didn’t noticed yet). Imagine you are in the middle of a dungeon with just half of a heart without items, you did some progress and you don’t want to lose it, or you are about to finish and don’t want to go get back… What you can do?
Just go to a checkpoint, save your progress and quit. Once you load your save, all that lost health is back. Cool right?