Because they bother to deeply learn what they need to do, to reverse these conditions, then apply that new knowledge process repeatedly to effect change, then adjust how they think and behave (and their lives) so it becomes harder to fall back into those 'out of wellness' states again in the future.
It is just a process - let this be your new positive (life-enhancing) obsession - The Calmness in Mind Process
In this short video clip from video 18 of my course, I explain why it is sooooo important to retrain your brain's RAS - The Reticular Activating System.
This should be taught in school.