I've never felt like it's taken much discipline for me personally, and I've never carried a balance on any credit card. I try to live far under my means and mostly just spend money on food, coffee, travel, and a laptop. Most of the rest of my "things" are hand-me-downs.

One "hack" that works for me is reviewing each transaction and paying the card in full every week. If I see it especially high one week then I spend more conservatively the next. I don't do any explicit budgeting, but being conscious of the big picture helps me.