I confess that I sometimes leave my helmet at home, whenever I feel like it's becoming too much a habit. Every once in awhile, at least, it's helpful to remind myself that helmets are not required legally, and not all that helpful. If we let it become too ingrained by automatically putting one on every time we go out, you start to feel like you have to, you start to feel unsafe or uncomfortable without it. I find that a good ride or two usually clears that right up!