The second part of the book is where the story really starts to pick up speed. When this part starts, the crew seem to still possess their motivation; they're conditions are slowly becoming worse and worse, yet they are handling it pretty well. Despite having to leave Endurance, the Shackleton and the crew remain in good spirits and seem to still have a lot of morale. It's very apparent how great of a leader Shackleton is. He always what he thinks is best for the entire crew, and this usually leads to positive results. Despite being in charge of the expedition, he remains humble and considers himself to be one with the crew.
As part two begins to come to a close however, Shackleton begins to become concerned that their current conditions are affecting the crew in a negative way. They are starting to lose their optimism and Shackleton wishes they still had their high morale intact. Their motivation as a whole is still present, although it is dwindling slightly. The crew is sure to encounter many more obstacles and hardships, so I think it will be intersting to observe they way the characters are motivated, and how this changes, throughout the remainder of the book.