In ways does internal journey mean?

Do you mean internal journey in general or related to the book title you are giving?

Just internal journey in general.

I think everybody goes through internal journeys. Some are intense and some are simply evolving over time. Self-discovery is a by-product of the journey. There are other reasons for internal journey and reflection but certainly self-discovery happens along the way. Conflict and reflection often lead to a different sense of self. This is how we grow and evolve as people.