Shannon, I hear you and will cheer you on!
Another way to redefine successful shopping: rejecting the not-best and delaying the good stuff to go back and think about what it will go with can be its own reward. I did just that for my birthday --- went shopping with voucher in hand, tried on bunches of things in three different locations across the city... came home empty-handed and happy!
A year ago, I'd have come home with bagfuls, and then taken days to unstuff and restuff my drawers, then saved the 'good' clothes and agonized over how to wear these new orphans! Yesterday, I felt I'd done well to determine which looks suited me and to take time to figure out which THREE specific tops would be best to get if that's all I got this year, and to give myself time to see if I could find them online, saving another trip across town (or cities!). AND it means I can think about what to wear them with calmly and carefully over days and maybe weeks, as well as getting a little ahead on saving for a more expensive purchase (shoes, in my case!).
I realize this is harder to do when thrifting, as stock turnover is higher, but sitting and prioritizing wardrobe wants can be as fun as window shopping too. And maybe you can play with different colours and silhouettes before you shortlist which you want most, then go shopping again for those specifics to help you stay on track? (For instance, if you decide you want a red shirt, you don't even look at the yellow and blue and whatever else is calling your name... or your wallet!)