I've never been a very girly girl, and comfort is definitely a lifestyle for me, but at the same time, I like feeling good about the way I look. I lead a very casual lifestyle. I am a combination housewife/piano teacher (I teach lessons in my home). My church is casual, so I can, and mostly do, wear jeans there. Actually, I'd guess I wear jeans 9 of every 10 days in the winter, and capris 9 of every 10 days in the summer. My hair is naturally curly, and I usually just let it air dry. I wear a minimum of makeup - usually mascara, eyebrow color, eyeliner, and a little bit of something to cover up some red patches on my chin and nose (lately I've been using the new mineral makeup that Physician's Formula has put out, and I really like that!). I keep a couple of dresses and nice slacks outfits for weddings, funerals, and shows, but I really hate dressing up.
Even so, I do find that I feel better about myself if I think I look good, casual or not. There are plenty of clothes that are comfortable but still look good. I weigh the most now I ever have, and I'm trying to lose weight, but I still think it's better to buy things that fit so I don't have to feel ashamed in public. I figure when I lose weight, it'll just be an excuse to buy more new stuff, and I'll enjoy that too
I agree with the poster who brought up the eyebrows - I do my own, but keeping them shaped up nicely makes an amazing difference to your whole face. A good haircut that works well with your hair texture and face shape is also a big morale booster. I wear my curly hair roughly shoulder length with some long layers, and I find my level of morale dips more easily if it's starting to lose its shape.
It's all about finding a balance, and knowing what makes you look and feel your best, whatever size you are, whether you're high maintenance or low, girly girl, funky, or casual - if you like the way you look, you're going to have a better day.