Buy a big, old, hairy horse!
Then you won’t be able to afford to buy clothes, furniture, make up, or tech, ever again! 😄 😄
Although this answer is slightly tongue in cheek as obviously you need to live in the countryside and have some land to do this; I find looking after an animal this size does lend itself to a sustainable non-shopping lifestyle because it changes your focus completely.
You are up before dawn and asleep at night early. You are totally in sync with the seasons; spending most of your time other than your day job outdoors doing physical work; mucking out, hauling feed, harrowing fields, mending fences. You are aware of all of the trees plants and wildlife around you.
Everything is make do and mend. Most purchases for your horse are second hand and you constantly scour local sales for pre-used tack or old equipment. A thousand uses for baler twine.
Every purchase you make for yourself eg Wellington boots is weighed up very, very carefully in advance for longevity. and every item is worn until it has holes or falls apart.
No need for make up or nice clothes as they just get muddy or torn. Everything is about warmth and functionality,
You end up with a load of manure so you make compost and start growing things on it and all of a sudden you have a veg patch. You eat your own home grown veg and then buy chickens who eat the scraps. So you have eggs. You start growing your own hay. You’re totally in sync with the seasons.
In summer you socialise outside; no one comes in to your home and no one expects your home to look chi chi anyway. People are more interested in how you made fire bricks from dung and your home made device that funnels rain water in to your horse’s trough.
In winter, you entertain in your kitchen. Or go to a local pub. Everyone is in the same boat feeling the pinch so you help each other out when two sets of hands are required. Presents are usually home made food stuffs like cakes and preserves. Or in summer, vegetables or flowers. In summary, a sustainable lifestyle is much easier in the countryside.