self-esteam
What Thomas and his coal-and-water-powered friends on the Island of Sodor each diligently strive to maintain in themselves, and to help improve in each other, as well.
Sir Topham Hat, Mr. Conductor, C-Junior, the station-masters and engineers and firemen and conductors, and the rest of the human-supervisors-and-operators team always give the engines praise where it's due, in an ongoing effort to keep their iron-horse friends' self-esteam up to snuff.