Don’t know what your character should/could be doing at any given moment in your story? Develop their interests/activities in four dimensions.
Professional: What do they do for a living? (everybody’s gotta make a living, or something like that, unless you’re a perpetual student.)
Public: What do they like to do in public? (with, for, or to other people. Group activities like making fun of people while they shop, hitting on women, being a jerk and correcting people on their grammar, club hopping, or being THAT PTA MOM.)
Personal: What do they like to do in their personal time? (it’s not advertised, but it’s not a secret either. Why, yes I do make scented candles on the weekends!)
Private: What do they like to do when they are alone? (they would NEVER do this in public or while anyone is watching. A guilty pleasure of sorts, like watching reality TV, spying on their neighbors, or keeping a running list of all their co-workers dirty little secrets, lol)
If you know what your character does in these four dimensions it becomes a part of them, and you’ll always have something consistent and within character for them do, or refrain from doing, or wish they were doing, no matter where they are in your story.
Much better than racking your brain for some random little thing on the spot.