Get a Hobby On
To add depth and interest--and **bonus** potential scenes to use for plotting--give your characters hobbies. What does she do when she's not working, falling in love, saving the world, or solving a murder? There must be something she longs to do when she's not doing it, something that helps her get in the zone and think, like Sherlock Holmes playing the violin.
A character's interests can reveal much about them. A fly fisherman, for example, is probably patient, meticulous, and longs for the peaceful solitude of the outdoors. On the other hand, someone drawn to performing--dance or theater, perhaps--is high-energy and enjoys bright lights and people.
"I collect spores, mold, and fungus." ~ Egon, Ghostbusters
Consider your own hobbies and what they provide for you--a creative space, focus, self-expression, physicality, ownership, satisfaction, an escape. What does your character need from downtime? Get a hobby on, maybe with one of these:
Cycling around the city... knowing all its nooks and crannies could come in handy for a hero or a villain
Extreme couponing... to cheaply stockpile for the next pandemic, perhaps
Binge watching old movies... because she's stuck in the past or depressed about her future
Stamp collecting, coin collecting, bone collecting, brain collecting *smirk*
Birding, Bugging, or Reptiling... Yeah, I just made up a word. Shakespeare said writers can do that.
The dark arts... photography, YouTube videos, writing
Mixology... designing the perfect smoothie, cocktail, beer, perfume, aphrodisiac, street drug, poison
Journaling... while watching the neighbors through binoculars
Knitting, painting, candle-stick-making... Hobby Lobby employees know this character by name
Walking, hiking, exploring... especially in places she shouldn't
Determining what your character's in to will help readers get in to the character. *smirk*