Smoking.
I can be around people who smoke for maybe a day or two at the most, but after that, I start to get unhappy and I know I probably wouldn't want to be around the smell every day.
I work hard and make choices directed at making things better for myself and preventing unnecessary damage and morbidity. Shouldn't I choose a partner who does the same? Smart and savvy is sexy. Smoking is not smart, savvy or sexy.
There are alternatives for people who enjoy nicotine, such as the gum and the e-cigarette. There's really no reason to use burning tobacco unless one also enjoys inhaling carcinogenic, emphysema-inducing combustion byproducts, looking bad and smelling bad. Imagine someone looking all haggard, in a wheelchair and adult diapers and having to cart a clunky oxygen unit around. Not exactly sexy, is it?
A woman told me that she's quit smoking, at least for the duration of her pregnancy, out of concern for the baby. Then I thought, why wasn't concern for her own health enough? Disregard for one's own health and hygiene, and the health and comfort of others isn't sexy.
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A boy and his dog can go walking
A boy and his dog sometimes talk to each other
A boy and a dog can be happy sitting down in the woods on a log
But a dog knows his boy can go wrong