I don't diet, but I do watch what I eat. I'm not completely into the "Primal" diet, but I do generally try to eat as little wheat as possible because even though my ancestors ate grains, their diet did NOT subsists of mostly grains (and fillers) the way our diets do now. I make sure that meat and any bread/pasta products are a side, and not a main course. Actually, we very rarely have a "main course" these days. A normal meal consists of some kind of starchy vegetable (potatoes, carrots, beets), a raw or quick-cooked vegetable (don't want to lose nutrients in cooking!), and a fruit or meat or "grain" side (husband can't have wheat so it is usually quinoa which is actually a seed, so it is more nutritious than most grains). So I guess we do avoid a lot of grains but I don't believe in restricting myself from anything, it's more about moderation.
My body can't really handle caffeine, I get severe stomach aches with just the tiniest bit too much. Since I don't restrict myself anything, I do have a bit of caffeine once or twice a week (sometimes more, sometimes less). I grew up an athlete, so I wasn't allowed to drink soda, luckily that took care of that craving, I probably only drink soda once a month.
I don't cut out certain foods so much as certain ingredients. I eat VERY little "high fructose corn syrup" which also appears as "corn syrup" on ingredients labels. I rarely cook with salt, instead I add a bit of salt to my plate at the table. I don't eat corn-fed beef, as it is higher in fat than grass-fed. I prefer not to eat animal products that have been treated with hormones and/or antibiotics because you really just don't know how those things affect you down the line. I don't eat most things that I cannot read what they are/ are obviously of chemical origin because our bodies evolved breaking down natural elements, not manmade ones.
That said, I love dark, heavy beer. I have at least one per week. I also love butter and cook with it often (but I don't use a ton!). I also eat meat, occasionally eat dairy, and grain too. It is all about figuring out how much works for your body. My husband and I have such different body types, if I ate as much meat as he does, I would feel ill. If he ate as little meat as I do, he would feel ill. It is a very personal thing, what kinds of nutrients your body needs.
As far as exercise, I live in a place where I can walk everywhere and that takes care of most of my exercise needs. Before I moved here, I would go out dancing 2-3 times a week (we're talking really dancing, flailing appendages, breaking a sweat, moving nonstop for at least 2 hours) and that kept me in good enough shape. I also used to do 20 minutes of yoga 3-5 times per week before I hurt my back. The key is finding something you really like doing. I hate going to a gym, I hate being on a treadmill, those things never worked for me. Lots of people I know do things like rafting or mountain biking or rock climbing and that obviously keeps them in shape. I'm not really into those things but I have managed to find that walking to the grocery store and riding my bike downtown and yoga/stretching are things that make me feel good and things I actually consider doing when I am bored, not just when I am feeling guilty about my weight/lack of exercise.
But what I always push on people is small, frequent meals. When I first became aware of what I was eating/how I treated my body, I started eating 5 meals per day and 2 snacks. I lost 15 pounds without exercising AT ALL. I have a very slow metabolism so that gave me the jump I needed.