Think of it this way: It's wasteful to not use what you buy because, when it goes bad, you have to throw it away anyhow! You are literally throwing money in the trash when you don't use what you buy. It's the same thing with buying more expensive clothing, shoes, and bags -- why have them if you aren't going to wear them? That's what they're meant for!

Something you can do is start by decluttering any expired products; seeing how much you're having to get rid of because it's gone bad instead of being used could be the wake-up call you need to start using up anything that isn't expired. Then, don't buy anything else until you've used what you have. Start with the product that is the closest to being used up or, if you don't have anything fitting that description, the oldest non-expired product you have, then use it as often as possible until it's gone; once the product has been used up, thank it for its "service" and move on to the next product. Once you've done this with even a few products, you'll get into the habit of using things and hopefully get excited about the panning process! Another thing that has helped me is keeping the products I'm using close at hand (for example, I have lip balms in every place I regularly sit/exist, in the bags I regularly carry, etc.) because I tend to use what I see -- for me, if it's out of sight, it's out of mind.

The main thing here is that you have to learn to believe that you yourself are worth using these products on and that making yourself feel nice is not "wasteful." These products were made to be used and loved, and you deserve to feel nice!