We often hold on to old party invitations, birthday cards, and address books for sentimental value. These things start to take up a lot of space if you save them all. Unless there is something truly precious or extremely sentimental about a particular item, it is okay to let go of it. You’ll have the memories regardless of whether or not you keep the invitation that you won’t see for five years, if ever again. You can toss Valentine’s cards from your exes as well. I can almost guarantee you’ll feel better if you do. S/he is your ex for a reason – regardless of who initiated the breakup.
For the items you want to keep: designate one box for these kind of mementos or put them in a scrapbook. You can do the same thing for all those pictures your kids draw. You don’t need to save them all. And trust me, they won’t remember drawing them all either.