You don't have a discipline problem. You have a system problem.
You've done the programs. You've read the articles. You've paid for the gym. Every plan worked, right up until the week it didn't.
One bad night of sleep turns into a skipped session. One skipped session turns into three. And then you're back at square one, wondering what's wrong with you.
Nothing is. Those plans were built for a version of your life that only shows up on good weeks. When the hard week came, they had no smaller setting, so they broke.
If you already know what to do but consistency is the problem, the issue isn't you. It's the plan.