You can lose weight on a good day. You've done it plenty of times.
It's the hard days your diet goes to hell.
The long days where you do everything for everyone.
The busy weekends full of chores, errands, and last-minute invites to eat out.
The nights you sit on the couch eating after everybody goes to bed, because it's the only me time you get.
On those days you don't need to try harder. You need to do something different than you do on the easy days.
Nobody ever taught you that, so you've been white knuckling your way through the hard days and blaming yourself when you can't do it.
You're not the problem. You were never the problem. Every diet you've done was built only for perfect days. The diets are the problem. Not you.