In no particular order (and click the title of each for info on where to buy):
I’ve seen folks who pick out a basic outfit (jeans, black tank, whatever) and stand in the same spot, every single (month/week/whatever) and take a picture. It may seem simple but it does something phenomenal. It gives you perspective! Sometimes we can’t see the changes we’re undergoing in the mirror. But those pictures are evidence. And since they are consistent (same spot, same type of outfit) you can’t go “well it’s because those jeans make me look smaller…but I’m really still big!” Nope. You are getting smaller and there’s the proof.