I once spent a very pleasant short vacation on a beach on Lake Michigan reading Peter Gabriel Bergmann's "Introduction to the Theory of Relativity," finding pleasure in gradually unraveling the notation, the mathematics, and the ideas, in a quiet and beautiful setting.
It always surprises me when I meet engineers who don't enjoy reading technical books, but different strokes and all that. It takes a kind of patience and persistence to unravel a technical text, which can be its own reward if you're not trying to solve a specific technical problem at the moment.