Although I put this fourth in the hierarchy of how I eat healthy, I will admit that it is a difficult one for me. I am a creature of habit, and it is easiest for me, especially when I am busy, to just eat the same things day after day. The way I avoid doing this is by eating a lot of similar things sort of on a rotation.
So there are some things I eat a lot. I eat organic field green and spinach mix that I can get at Wegmans very cheaply. I usually eat it with thin slices of turkey. I roll turkey around huge bundles of greens, and it is so good! I eat frozen berry mix mixed with plain Greek yogurt often. I have coffee with cream every day. I regularly eat the same types of vegetables that I like sauteed and raw and steamed and roasted. I mix it up by trying to not eat the same things every day. If I had a can of beets yesterday, I probably won't choose to eat that today. If I had a Luna bar, I may not eat another for three or four days. If I had fish yesterday, I will choose beef or pork or chicken today.
The reason I mix it up is twofold. First, I want to be able to maximize the nutrition that I get from my food. If I am always eating the same things, I may be missing out on some things. Second, I am never 100% sure of the safety of our food supply. Eating a wide variety of foods minimizes anything harmful that I may be ingesting.