What makes an activity a hobby
A hobby is something you choose to do repeatedly for interest, enjoyment, or skill building outside your obligations. Coloring fits that definition whether you spend five minutes filling one region or keep a binder of finished pages and experiment with new supplies.
There is no required skill level
Some people collect pencils and study color theory; others print a page when they need a quiet break. Both are legitimate. You can work on paper with the free printable collection or use the online coloring tool when you want less setup.
Keep the routine small enough to repeat
Store a page and one favorite tool together, choose a regular time, and stop before the activity becomes another obligation. A hobby works because returning to it feels easy, not because every session produces a perfect finished image.