Total vegetarian is never suggested.
Doctors also recommend the diet including non-veg. In my opinion both are essential.

Different doctors recommend different things, there is no one diet that every single doctor recommends. There are plenty that view the choice of being a vegetarian favorably. My uncle is an MD, and has been a vegetarian for years and years. Nutrition is a pretty complicated field.

My understanding is what gives being a vegetarian a leg up on most American diets is that the typical diet is full of both WAY too many starches, and way too much fat, which together is a truly terrible combination. If you remove one or the other it's a step in the right direction. Combine that with the hugely beneficial effects of eating a diet higher in fiber (which a good vegetarian diet will be), and you can see that the reasoning behind eating more vegetables, less meat is pretty sound.

Not eating meat isn't unhealthy for you, getting protein is the issue. Of course eating meat in reasonable quantities isn't unhealthy at all either, and is an ideal source of protein. Eating too much (especially red) meat though, yeah...among other things it's pretty well known that both your cardio vascular system and your colon health can pay a price for that.

Many people are having this misconception that vegetarian diets do not provide enough protein or necessary nutrients to fuel an athlete, but in fact this is not true at all. Athletes just have to athletes must make sure that they are consuming enough of the main nutrients such as carbohydrates, protein and fat, while getting enough vitamins and minerals which all are present in the full vegetarian diet.

Doctors in general are woefully under-trained in the science of nutrition.

What gives vegetarianism and veganism a "leg up" is the fact both tend to be very low in calories. Calorie restriction remains the only demonstrably proven method of preventing cancer in studies.

Calorie restriction combined with a diet relatively high in carbohydrates seems to be quite healthy. A diet relatively high in protein and fat seems to be quite healthy as well, especially in the presence of considerable physical exercise. Diets high in refined sugars and flours seem to be not so healthy. Diets high in calories, unless accompanied by significant intense physical exercise, seem to be not so healthy.

On the subject of nutrition my fall back has always been, why argue with 40,000 years of evolution. Humans survive on meat and plants, any modern diet that attempts to substitute or change that is playing with fire IMO.

Basically we need to consider food sources that are as close to their natural state as possible, the best choices. People will often say, I can get my protein from other sources, OK but protein is not the only thing in meat that the body needs. Why try and recreate something that already exists in nature? You'd be much wiser to beware of processes used in the distribution of the food you eat, than substituting on a base level. Anyone who has ever had true organic steak vs. most store packaged meat will tell you the difference is significant.

Even that though, the body is quite robust. As long as you stay centered on your diet plan, you don't have to get crazy about trying to eat healthy. The body can take a lot more than I think people realize. (this is not a license to pump poison in btw).

Exercise is key, the benefits to physical exertion are so profound that if it could be put in a pill it would be the prescribed medicine in human history.

Disease has multitudes of factors. Poison (cigerettes for example), genetics (gene that mutate into cancer for example) environmental causes, or just bad luck and we don't know why.

Just my 2cents.

Totally agree.
Exercise can alter your mood for the better as well. I find that if I feel angry or anxious about something, a good workout will have me feeling more relaxed and clear-headed.