What it Means to Grow Up: A Guide to Understanding the Development of Character, Fritz Kunkle, 1936.
Just finished this book and I highly recommend it. Quote from the preface below and link to the free PDF or eBook on archive.org.
We must teach youth to face calmly the facts, the tasks and difficulties of actual, everyday life and to master them, for it is not a cold abstract theory or a world-forgetting ideal morality which we are called upon to transmit to the new generation. Which means, at the same time, that we must show how one can recognize, understand, and master one’s own peculiarities, one’s own tasks, and difficulties. We must teach the art of growing up.