Diet and Nutrition

Lately I've been picking my friends' and families' brains (this has been inspired by countless cookbooks, diet philosophies and alternative health books) about what healthy means. How does our society define physical health?
While meandering through definitions on the web (like Wikipedia) proper nutrition and regular exercise looked like key components.
Regular exercise is almost a given. There are better ways than others to break a sweat, but (for the most part) doing any amount of movement on a regular basis always seems better than none. Good to take the middle road here. Not too little, not too much. That always seemed to work for me, anyway. I know that too much exercise can create a great deal of stress on our bodies, but other than that I'm somewhat clueless.
Diet and nutrition are trickier words even. Raw foods, the USDA food pyramid (which almost everyone I know thinks is incredibly outdated), vegan, vegetarian, macrobiotic, whole foods, low carb, cleansing, detoxing- which diet plan to choose when? How does one approach proper nutrition and healthy eating when there are so many philosophies to choose from?
Most of them sound pretty plauable, as well. I've gone raw for a while, done vegan, wheat-free, vegetarian...I've fasted, detoxed...but I usually go back to a mostly whole foods based diet. Not that I'm saying whole foods is better than any other diet, but it is generally the basis for many other diets I've been interested in.
I will note that my 'back to basics' type of eating habits (foods that aren't processed or fried, are organic and preferably local) make me feel much better than going out to eat, for the most part. Some dining establishments cater to those looking for 'healthier' eats, but usually eating out causes indigestion and bloating.
However, even though whole foods has been making my body feel pretty good lately, I think a cleanse or raw food fast is in order soon. Usually giving my body the ability to (deeply) pay attention to how certain foods and combinations of foods make me feel (at different times) steers me in the best direction.