From my theme calendar for the month called Risk.
Credit: Stock Connection Distribution - Alamy.
Writers are advised to provide their main characters with hobbies and habits to assert individuality and round their personalities. Hobbies not only advance character as well as provide for possible reader identification -- as the comedian Fields ( I think) said " a man who hates children and small dogs can't be all bad" -- they also allow opportunity for plot leverage.
Such hobbies and interests are perhaps a more vital component of character development in a series than a stand-alone. Hobbies remain a staple for many cosy mysteries. Hobbies, especially obscure ones, also allow a reader to acquire information pleasantly without feeling instructed.
The very best example I can think of at the moment is Rex Stout's Nero Wolf, a private detective who seriously cultivates show orchids and employs a gourmet cook. (Warning: don't read him when dieting.) On many occasions, both orchids and meals operate as more than mere background and become essential to the unfolding action.
The worst -- or most limited -- example that occurs to me is L.K. Hamilton's Anita Blake's affection for stuffed penguins -- a habit that appears to me to be mechanically inserted to show that Anita has a mushy, vulnerable side to off-set her kick-ass attitudes. In the few of the Blake series I've read, the passive penguin collection provides a rather obvious character balance and nothing more.
To be fair, the more go-go action-oriented and fast-paced a story is, the less logical opportunity for diversional moments of quiet puttering and exposition.
That said, I think my Lillie might need a specific hobby, some activity beyond the faint suggestions about her herb garden. Perhaps she will write poetry.
Does your main character have a hobby?