"I like Daniel Gross’ framework for learning. When I interviewed him, he told me to build a video game for myself. Like a video game, productive projects have multiple levels. They follow the Goldilocks Principle: not too easy, not too hard. The learning project needs to be challenging enough to demand focus, but easy enough to make consistent progress. That way, you can enter the optimal state of learning.
If you get stuck, the “video game” is too hard. When this happens, you should stop. Work on a smaller step or retreat to a manageable challenge. Otherwise, you will lose your motivation to continue learning. Conversely, if you’re bored, the video game isn’t difficult enough, so you should attempt a tougher challenge that you haven’t seen before."