What does habit mean?
the term habit means a particular behaviour pattern regularly
followed until it has become almost involuntarlt
An acquired behavior pattern regularly followed until it has become almost involuntary.
When you say that someone is a 'creature of habit', you mean that this person is so comfortable in their current lifestyle that they have for the most part ceased to be spontaneous in any way. Most everything that they do is done by force of habit rather than by instinct (as animals do) or by conscious decision or by whim.