Answer: Based on this excerpt, I think Xavier does not persevere enough. His sister hid the mysterious item in the forest so he can learn to persevere. But then she passed away, and she never got a chance to reveal the item. Xavier should've learn to try harder and never give up.
It is somehow related because Sad Perfect is a book about a girl who has an eating disorder, as you know this is not an easy thing to deal with so it would not be uncommon to hate your life. It's not a quote from the book but it can relate.
