I've always been excellent with living within my means, came here with no debt, and am a zealot for YMOYL.
And...I love YNAB!
When I first bought it, I didn't take to it.
Two years later, I gave it another shot, fell in love, and have been wildly happy with it.
My keys:
1. I was willing to try it again, in a new headspace.
2. I was willing to come up with a couple of workarounds* to make it fit my own situation.
3. I started out by entering my money stuff daily. This dropped my already-good spending dramatically.
4. After about 8 months, and all the spending hacks I could think of, I felt my motivation for manual entry waning, so I allowed myself to move to downloading from statements.
I continue to be wildly happy with it.
* I considered approaches for: arriving to YNAB with no debt and a solid buffer in place; entering business info as well; entering reimbursables; categorizing and tracking funding accounts that don't run in cash; moving to an annual budget. I've found YNAB to be as versatile as I could be creative.