Robert Llewelyn's "Our Duty and Our Joy" is, next to the Bible, the most helpful book on the spiritual life I've ever experienced. I do not say "read", but rather "experienced", because it is not a work to be read as information but rather a book to be absorbed for formation - one best taken, therefore, in small doses. It is not to be devoured but savored.
This is a slim volume, written in an English that is plain but articulate. It underscores a massively important part of Christ's and Paul's message that is seldom given its due from the pulpit or elsewhere. It hasn't changed my view of the Christian message so much as made me profoundly more aware of its implications in everyday life.
The book consists of 52 chapters, each one no longer than a page. I find the most useful way to go through the book is, daily, to read one new page after rereading the previous page. But this is simply a personal preference. Someone else might prefer spending a week on each one-page chapter, thus completing the book in a year. I am currently going through it for the sixth time and finding it still fresh.
The one huge fault here is that "Our Duty and Our Joy" went out of print long ago; it is thus available on the secondary market only and, even then, only from England. Why it has not been reissued is beyond my understanding.
A final word: I am a Catholic layman and , as far as I can make out, Robert Llewelyn is an Anglican priest. No matter - this book is for any present or aspiring Christian.