I agree that a certain amount of practice is needed to get and remain sharp (but actually suspect that 40hrs is too much), but I disagree strongly that a “love” for their craft is a necessity. There are tons of incredibly competent engineers who do it as a job to make a living without it being their main passion. I don’t expect my plumber to be in love with plumbing, I just expect them to be competent. Claiming that loving programming is anywhere near a necessity to learn new things is to completely ignore how people in any other profession learn new things.