The 7 Habits of Highly Effective People — Stephen Covey
Covey’s classic, The 7 Habits of Highly Effective People is a book I would call stealth spirituality.
Covey was Mormon but the book was written for a secular audience. It’s a pretty easy read, but takes a lifetime to master. I recommend it here because it’s a clear and accurate description of a Westernized 8 limbs of yoga.
In order to avoid classic spiritual pitfalls like spiritual bypass, and spiritual materialism its essential to focus your spiritual path on actual self-mastery. This book is largely perfect for that. The only real problem it would present to advanced students is the concept of time. Future tends to melt away after a while.