This is a good tip. I do the same thing when reading math books. Trying to pick up advanced math on your own can be really challenging because there are almost

This is a good tip. I do the same thing when reading math books. Trying to pick up advanced math on your own can be really challenging because there are almost no worked examples of, well, anything past the undergraduate level. The author supplies a series of exercises at the end of each chapter, no solutions, and you're expected to provide the rest. Fortunately every theorem that is actually presented can be viewed as an exercise that was too challenging to state without proof. Now every time I hit a theorem, lemma, etc. I do exactly what you describe. (The paper is really necessary, I'm incapable of not reading ahead and peeking at the solution, at which point the "problem" is ruined.) Often my solution is way off the book's, but this is the best/only way to "learn by doing" when it comes to higher math.