hi, well i haven't studied it fo anything but, I'd say the inner journey would have something to do with
sam: self-actualisation; he grows in character and stability. Example being his mucked up lifestyle as demonstrated by him trying to kill himself at the start and the car scene. The building of this house gives him a project, allows him to bond and understand his father etc.
george: realising that he can no longer sit back and let whatever happens just happen... his illness gives him a reason to persue his unfinished goals. He is literally living every day like its his last. His personal journey makes him come out of isolation and he finally takes his responsibility for his troubled son.
robin: she finds out alto about her life; her present husband really just doesn't satisfy her emotional needs. He doesn't hug their children... She realises what she liked about georges personality for those first few years of their marriage.
alyssa&colleen: well, stuff- i can't be bothered with that right now...gotta go but good luck.
sorry if ur like well..duh! it's just of the top of my head.