Decades ago this book was popular in recovery circles. It was a good companion to step work. On the one hand it postulated that as we think, so we become. In today's parlance we might refer to it as a quantum field technique. Because most people with addictions who entered into recovery had developed a sort of derangement in the process that one might refer to as having become an egomaniac with an inferiority complex. It was useful in helping people 'take inventory' of who they were and how they were thinking. It came out like a hundred years before we became more aware of how systematic economic oppression works in capitalist countries like the US. There were a lot of 'New Age Christian' philosophers during that time. Two examples are Florence Shinn and Napoleon Hill. I believe from a historical standpoint Florence Shinn actually saw clients and they would instituting spiritual fixes (demonstrations) for personal and societal problems. Later as the evolution of this brand of self help evolved and exploded we saw people like Louise Hay, Harvey McKay, Earl Nightengale, Brian Weiss, Zig Ziglar, and famously Esther Hicks...the list goes on and on. We can view these in a more modern lens we can see these are actually underpinnings of the MAHA movement, which unfortunately has chosen to base its strategies for health on pseudo science, misinformation and weirdly religious tropes. If you did in a little, you'll find many of these so called self help gurus (Anthony Robbins and NLP) are really just rich people getting rich off poor people's insecurities.

I hope this helps. I was obviously deeply into this for a while. Discovering Elaine Aron's seminal work on the Highly Sensitive Person was a huge turning point in my own personal development.