Be an ongoing struggle. Same thing with other issues like Bipolar Disorder or psychotic disorders. A lot of these things don’t simply go away because of healthy living. Many of them may not be preventable. Genetics can be out of one’s favor.
On the other side of the coin, living a healthy lifestyle and being properly raised by parents (like the OP suggested) is such a good way to be set up for success. We should all strive for a healthy life. It’s just important to note that changing behaviors may reduce mental illness problems but may not make them disappear. Mental illness is far more complex than we probably realize.
It’s kind of like saying someone with diabetes needs to just start exercising and losing weight and then everything will be fine. Well, for some people they can drop their A1C by a large margin based off of lifestyle and habitual changes. Others may only get minimal returns. It doesn’t mean the means weren’t worth it, but we don’t all get the same end result.