The Book Thief--Death says Liesel was a girl "with a mountain to climb." What is her mountain, who are her climbing partners and what is her obstacle?

Death says that Liesel is a girl "with a mountain to
climb" because Liesel is trying to survive the harsh reality that is created by the
war.  Liesel is trying to cope with the emotional stress that is around her, and this is
her mountain to climb.  Liesel is given to the Hubermanns because her mother can no
longer care for her after the father is taken away to a concentration camp.  While on
the way to the Hubermanns, Liesel's brother dies of illness on the train.  This haunts
Liesel for a long time and later is compounded by other trauma such as threats of Hans
and Rudy being taken in by the German army, Max's hiding in the basement, and prisoners
being taken to Dachau.  The other characters in the novel--Rudy, Rosa, Hans, and
Max--experience these fears with Liesel and they must all cope with the horrors of the
war.