Losing Your Purpose

I have a question for you all. It initially pertained to writing but could be translated to life in general.
Have you ever lost track of a goal? When you start a summr job, was it just to make money but then by the end of it your focus had shifted? I wonder if that has ever happened when someone is writing a story. What if you set out on this journey... initially it was to find adventure or some buried treasure. But what if along the way, you found something else? What if you found a community, a sense of belonging? What if you found the basecamp to some shady underground facility? (I did say "buried" treasure, remember.) What if you found something better? What if you found something worse? In short, what if you lost track of why you set out in the first place, but the things/people/places you discovered along the way were more fulfilling in some way than what you had originally intended?
It's just a thought. I've been thinking of "Story E" lately and there's a part that involves a forest and this community of people who live there. They are a cross between Robin Hood and the Mud People from Terry Goodkind's Wizard's First Rule. One of the characters starts to wonder if he/she should really pursue what they set out to do, or if he/she could make a life with these vagabonds, these outlaws. A content life. But that character struggles with the reasons behind his/her original intent. Would it be an insult to the people they set out to please to abandon their journey of peril and settle down, while always leaving a part of themselves unquenched?
Am I making any sense here? I'm really curious what other people think about this, especially for characters in a book. I know it's like a rule that the main character always keeps their quest in mind, but for argument's sake, don't people lose track of their purposes sometimes? Don't intentions, meanings, and trains of thought get blurred occasionally?
Discuss....

-Grace