I can't say that I was ever eating really poorly, but overall since last year when my overall health, and mainly my digestion came down to its lowest point, when even dry bread had me throwing up, I have mildly altered my diet, with amazing results!
I have entirely stopped eating wheat products, according to my Dr. I am not Gluten-intolerant. But going on well-being and my body feeling, wheat is what had me down. I have to say it was quite a challenge at first, but about a year later, the only product I do miss a bit is traditional bread! Although there are some excellent non-wheat solutions out there.
Other than that I have sharply reduced my meat intake, not out of vegetarian principle, but rather because I came to the point where it just doesn't taste right anymore. I'd rather eat meat once a month or even only every 2 months, but then give me a really good piece of meat!
Furthermore I changed to purchasing my products as locally as possible, and as a first test run I am growing Bell Peppers and tomatoes on the balcony. And I stay away from Fast Food, and processed foods as much as possible, as George Carlin put it: "imagine the people who are processing your food.."
One of the links I can absolutely recommend if you are looking at improving your diet is: www.foodmatters.tv
From that link I also got the idea to eat 2 avocados a week, with a lot of garlic, and those 2 have been doing wonders to my liver, which feels much younger and healthier!
What I can also say, is having a healthier diet, with lots of fruits and vegetables actually got me to enjoy my food even more, and I love delicious food!