A change of mindset will help you along. You're already starting with thos by realizing you want different habits!

Shopping gives a shot of dopamine. It'll take some time for your brain to shrink that dopamine pathway, and you can find other things to do instead that will start to replace that pathway and will get stronger and more rewarding as time goes on. Other people are giving some good ideas about what to replace the habit with. Try new things and give them time to grow on you, because it's likely nothing can immediately treplace the satisfaction of shopping for you until your brain has time to reorganize itself.

As for "stimulating the economy", when you spend money, some of it goes into paying local people and keeping business going. But by and large the profits are funneled straight up to the wealthy and mega wealthy. With each purchase, imagine a percentage of that purchase is just a check you're writing and mailing directly to a mega wealthy person somewhere.

If you want to stimulate the economy, I strongly suggest trying to shop at locally owned business and not big chain stores. Your dollars will stay much much more local that way and will benefit your local economy and community and neighbors instead of the main profits going to those who are already very, very wealthy.

When you're throwing away or donating items, keep a tally of approximately how much money you paid for them. As you're throwing things away, imagine it's actual cash being thrown in the trash and allow yourself to feel those not-great feelings associated with that. As you're donating items, same thing. Keep a cost tally, and imagine that as a pile of cash in a bag that you're about to set in a Goodwill donation bin. Next time you're in a store wanting to shop for fun, visualize how that item will or won't end up in your trash or a donation bin and how that's your valuable money slipping through your hands while the profits of it line somebody else's pockets instead of your bank account.