Vs 12 tells us that even Jesus who was God personified knew the importance of quiet time, so therefore we should learn from him.

Vs 40 tells us that a student or servant is not greater than his teacher or master,but that someday he too will be called a master or teacher if he be prefect or undergo thorough training. That's to say there is time for everything, a time to be a slave, student, learner, disciple, servant etc and also a time to be a master, lord, teacher etc.
So as Christians we should know our place,learn fast if you are a learner, servant, student etc so that we will someday lead, teach, educate or train others don't keep too long at one phase. Move forward.

See you at the top.