In my point of view best mental status can improve someones health too much. Honestly if you are very much sick and your mental health is good, it will help to make you healthy because your whole body is under the control of your brain. According to my observation the people who have good mental health and happy in life, they have long life, strong and healthy physique.

In my opinion, (You can also say "from my point of view," but "in my opinion" is better.) having the best mental health can improve someone's overall health (Adding "too much" makes it sound like it's a bad thing). Honestly, if you are very sick but your mental health is good, it will help make you healthier faster (Do you mean healthier faster? That's what I assume you mean because it sounds like you're comparing the recovery time of having strong mental health to having weak mental health.) because your brain impacts your body (I understand what you meant, but "under the control of the brain" sounds like something I'd hear in a science fiction movie). From my observation ("According to" is used when the information isn't yours. For example, "according to the newspaper" or "according to my mom."), the people who have good mental health are happy in life and have a long life and a strong and healthy physique.