I hold the door for old ladies. They have manners. They always say "thank you" when you do it. And they always look genuinely happy that someone showed them a kindness, and they'll smile, which then puts something positive into my day.
Or I'll hold it for a mom if she's got her kids with her. She may not have the energy to smile at you because the kids are driving her nuts, but you know she could use all the help she can get. At some point, she'll remember it and be happy someone helped her.
Single women can get their own doors. They rarely say thanks, and somehow give me the impression they feel entitled to my time being used to hold their doors. Feminism cuts both ways. You want to be treated like a man? Get used to no one helping you with a door.