Thank you for your comment.
Yes, we can treat mental health and we have been doing for a number of years using various resources from medication to alternative treatments.
You have used the example of a broken leg. Let us say a person breaks their leg today and we treat that person and he is better. What stops that person's leg from being broken again? Nothing, physical injuries happen all the time and we should not assume that if we have treated once, then it will never break again.
Regarding mental health, of course, it is different from physical health but we should not ignore it. Mental illnesses are 'illnesses' and should be looked at and treated seriously and effectively.
Success with mental illnesses looks like a person living a normal life, with a stable mood, happy, content, able to go outside, able to relax, able to appreciate life and more. These are the simple things that people suffering from mental illnesses can not enjoy and take pleasure from.
I hope that this helps you in appreciating mental health a bit more and that the individuals suffering from it are not just putting an act on.