It's not the stuff you were throwing away, it's the memories associating with the stuff. E.g. You pick up a shirt to throw away, then you remember the time you used to wear the shirt, the girl you kissed wearing the shirt and how you no longer talk to her.
You pick a book and remember it was your dad's favourite.
So it's the memories.

Solution.
Don't plan to throw away stuff, whatever you run into just throw away.