We accept the fact that shopping is not a hobby.
I had a eureka moment about this when I was expecting my second child. I didn't shop all that much -- not as much as some people -- but I did like finding a bargain . . . even if it was for something questionable, something I might not need or something that was an upgrade of a perfectly good item I already had . . . Anyway . . . I was clearing out what had been a guest bedroom/hobby room so it could be made into a nursery for the second baby . . . and I found bags and bags of things I'd bought and shoved into the closet. Some of them were things that I'd bought with a certain thing in mind (I specifically remember that there were bags of pink first birthday items -- and at that point my daughter was almost three). And some things I'd bought thinking, "This'll be a great gift for someone sometime." Yet there it sat, multiple Christmases and birthdays having passed by. And some bags held practical things that I really could've been using: toothpaste, maternity clothes . . . yet I hadn't realized they were there! Clothing items were a problem: I had shirts that matched nothing (which is why they were on clearance in the first place) or toddler-clothes that my daughter'd outgrown without every wearing -- or, even worse, things like toddler shoes I'd bought a second time, not realizing I had black Mary Janes in that size already.
At the time I'd bought these things, we'd been really scraping by financially . . . and it really hit me that I'd been worried about money, had skimped on groceries, was driving an old car . . . and yet AT THE SAME TIME I'd bought this quantity of junk that was stuffed into a guest bedroom closet and was never used. It was a wake-up call for me. I'd thought of myself as thrifty because I was buying things at good prices . . . but the reality was that things I didn't need were wasted, no matter how low the price. I had a decent yard sale, but a yard sale never actually MAKES MONEY; rather, it just recoups a portion of the money you've already spent.
Why'd I do this? It was that I was using shopping as a hobby. I didn't plan it. If I'd been thinking about what I was doing, I would've made better choices. I'd stop at the stores on the way home from work -- just as a diversion, just because it's what people do -- and I'd buy stuff. Just stuff.
And often while I was out, I'd find something on sale -- something I needed, something that was a good bargain, something I could justify buying. Or I'd see something that I hadn't even thought about wanting -- a necklace or a baby outfit -- and then I'd keep thinking about that item 'til eventually I'd go back and buy it. If I hadn't seen those things, I wouldn't have desired them. And it's so easy to justify purchases: It's for the kids (do they really need another toy? does a growing kid really need more shoes in this size?), or it's for our vacation, or we can always use more glasses in the kitchen.
Have you ever heard anyone call Target the $100 store? You can go in there intending to buy two specific things, and you come out having spent $100. That's the mindset you have to overcome.
From what you're saying, I'm sure you're doing the same thing: Using shopping as a hobby. So it's a matter of changing your habits. Keep a running list of things you really need, and decide that you'll shop only at scheduled times. Calculate your needs carefully and set aside time/money appropriately -- the theme here isn't, "Do without"; rather, it's, "Don't go overboard". How many pairs of jeans do you really need? How many pairs of sandals? Remember that "window shopping" leads to buying -- of course, then, there's gas, time, and often a soda or a snack while you're out. Calculate the total cost of shopping.
So you need something else to fill your time. You know your interests. Choose something!
A related topic: A friend of mine told me once that there's a Catholic principle about avoiding places or situations that cause you to sin. So if you're an alcoholic, you should avoid going to bars. If you're an over-eater, the buffet is a poor choice for you. Putting yourself into those situations TEMPTS you to do what you know you shouldn't. If you're an over-spender, that theory says you should stay out of the stores when you don't have a specific need to be there.
. I'm not a big shopper, but I will hit clearance sales and the like, and I also buy alot of gift items online (clearance of course). Just yesterday I did one of my rare shopping trips..I needed a few clothing items for an upcoming trip so went to Penneys and bought a few things on sale, and also a few clearance clothing items for gifts for grandkids and DH a pair of work pants (he's a vet tech and you wouldn't believe how quickly his work pants get ruined). Usually I buy clothes from thrift stores, eating out is usually Wendy's or Arby's, our cell phone is TracFone, no gaming systems, no big flat screen TV, modest house, old furniture, etc. In a month we'll have everything paid off except the mortgage and a few straggling medical bills. That feels better than any stuff.
My "Old tRusty" was a '97 with 216K miles, more than its share of body rust (lots of salt and chemical melter here on the roads in Maine), and needing about $3000 in front-end repairs to pass inspection next November. The "new" van is a 2007 Grand Caravan with 53K miles on it. They gave us $1200 in trade for my old van, which is about 3 times what it was worth, and they came down in price, and the payments are within the budget. It'll mean tightening the belt for awhile... but we'd been driving "Old tRusty" for 10 years and it wasn't smart to keep repairing it, because once one thing was finished, another would have come along. The interesting thing was I didn't know we were buying yesterday... I thought DH just wanted to look at a few vehicles and do some test-driving. We bought the first one he saw (although DD and I have been test-driving several vehicles in the area for a couple of weeks...). The thought of payments doesn't make me happy, but otherwise I am psyched 
We can spend hours at Target or Ross and walk out empty-handed. We try not to buy anything we don't need.
