If you are as successful and as happy as you want, then you are on the right path. But regardless of what any book says, there will always be people who are willing to work harder than you, especially if you max at 40 hours per week. Especially in a new job, I try to work harder than anybody.

I love to work, learn and my job means a lot to me. I don't work 50+ hours a week because they tell me, or because I have read a book.

I always love it when a new project is full of people who lecture others about work-life balance. It usually means "i don't want to work more than I should, and you should not too, so we are all even". But I do it anyways, and 80% of the time it pays of very well.

Do what you want, and maybe you are a genius who can do a lot with little work. But don't tell others working hard is bad advice either.