Boredom in a subject usually means you’re standing on the surface. Dig one layer down.

Boredom is often a signal about depth rather than about the subject. At the surface, everything is definitions and procedure, which is genuinely dull; one layer down are the arguments, the unsolved parts, the reason anyone cared enough to invent the procedure. Most subjects only become interesting at the point where you know enough to see the questions.

When something bores you, go looking for the disagreement inside it. Find out who fought about this, or what problem the method was invented to solve. If it is still flat after that, you have learned something real about your own direction.