What is the difficulty for shepherds to plant trees?

The difficulty lies in being alone, insisting on planting trees for decades, and turning the barren plateau into a paradise with trees and streams.

The Shepherd Planting Trees, also known as the Tree Planter, is a novel written by the French writer Jean Giorno. It's about a lonely shepherd who has turned the mound into an oasis through persistent tree planting for nearly half a century, proving that lonely people can also find happiness.