Your brain tells stories to make you believe you're doing just fine
Humans enjoy hearing stories -- it helps us make sense of the world. Without the ability to make stories, every event would be a disconnected piece of information without any precedent, cause, or consequence.
The only problem is when these stories wind up sabotaging your diet or lifting program. For example, if you're not keeping track of the foods you eat, you may not be aware of when you're "treating" yourself. Months down the road, you wonder why nothing's changed, even though from what you can remember, you've been eating everything you're supposed to.
Same thing for workouts. You may go into the gym and jump on the treadmill, do a few machines, and get out. That works for a little while, but after a point you may become frustrated at your lack of progress, especially when you keep telling yourself that you're lifting and doing everything that you should. See how that story begins to unfold?