If you don't give every dollar a job it quits and finds one itself
People always ask where to start with a budget and honestly the answer is dumber than anyone expects. Just tell every dollar where to go before the month starts. Income on top, every bill and every spending category underneath, until there is zero left unassigned. Not zero left in the account, zero left without a job.
The first time you do it, money starts showing up that you couldn't account for before. Random subscriptions, food delivery, stuff that was just gone by the 20th. Once every dollar has a job written next to it, the leaks slow down, because skipping the plan now means actively pulling money away from something you already chose.
It's not a spreadsheet thing. Paper works, a notes app works. The tool matters way less than the one habit, which is doing it before the money shows up. After payday your brain has already spent it twice, so the plan has to exist first.
tbf it falls apart the second you skip a month. One month of telling your money where to go beats a year of hoping it behaves.