When her grandfather asks her if she wants to go out to the mountain with Peter and the goats in chapter III, Heidi is very excited. She is far more excited than Peter because this is all new to her. To him, it is what he does every day.

Heidi, for example, is so excited at seeing a large bird that she wants to climb up and find its nest, an idea that Peter pooh-poohs as impractical:

"Oh! oh! oh!" exclaimed Peter, his disapproval of Heidi's suggestion becoming more marked with each ejaculation, "why even the goats cannot climb as high as that."

Heidi is similarly excited over the goats, as she has never before seen their games and "capers." These are fascinating to her. Peter, in contrast, sees the goats every day.

Likewise, Heidi is excited and astonished at the beautiful colors that light up the mountain as the sun begins to set:

"O look, look! the high rock up there is red with flame! O the beautiful, fiery snow! Stand up, Peter! See, the fire has reached the great bird's nest! look at the rocks! look at the fir trees! Everything, everything is on fire!"

"It is always like that," said Peter composedly, continuing to peel his stick; "but it is not really fire."

This a classic example of one person being excited at all the newness of a scene that is commonplace to another person. Also, Heidi has a very lively and enthusiastic personality, which adds to her ability to be excited.