The current trend in productivity books, personal coaches and bloggers [...] is to stuff more and more things into each idle hour, until you are working all waking day. But you don’t need to move really far to find some other kind of advice: In a book published in 1910, How to Live on 24 Hours a Day, Arnold Bennett already suggested that you need to claim several hours a week for improving yourself.
S. Aroca-Ouellette, and F. Rudzicz. Proceedings of the 2020 Conference on Empirical Methods in Natural Language Processing (EMNLP), page 4970--4981. Online, Association for Computational Linguistics, (November 2020)