Dunno, Tom. Setting aside some time for learning programming languages sounds like a good idea. Do you meditate or do yoga or anything like that? Those aren't terribly time consuming and you can do them on your own-maybe they would help you get to where you want to be mentally (and yoga has physical benefits, obviously). Don't know if you like that sort of thing, but maybe those books of puzzles like Mensa does, or some of the 'Very Short Introductions' books (or similar) might be a way to get a little mental exercise in. Have you thought about changing to a fixed rota and using your knowledge in other areas to bring your income level back to where it would be doing shiftwork (e.g., starting your own business, taking on some part-time work, freelancing). Good luck escaping the mental lethargy.