McCandless mostly had just a sense of adventure that just would make him travel to various locations.
Chris was focused on going on his trip even after his parents said they were worried and didn't want him to. On page 119 Carine explains that if you try telling Chris something, he will just go and do the opposite.She said "If you attempted to talk him out of something, he wouldn't argue. He'd just nod politely and then do exactly what he wanted". That's why Chris also wanted to travel. He also wanted to go to Alaska in the first place was because of his favorite author Jack London.