There are many self-help and personal development books available to us. Some people are totally into them, believe, and practice what they read, and some are completely on the opposite spectrum. Personally, I am not an expert in any of the teachings, but rather a person who wanted to pursue ways to improve myself and my life. I was feeling stressed out, anxious, and fearful and wanted to do something about it. I started reading many of these books and they made an impact. It is not something you read and instantaneously you are feeling better. It involves continuous practice and changes in behavior.
Depending on the type and the author, these books teach and use different tools you can start applying and slowly start feeling better and perhaps even change some of your future outcomes. Whether those tools are based on self-love, self-confidence, present moment, the law of attraction, frequencies, energies, source, universe, all of them are meant for you to be better than you were before. They can help you to be the best version of yourself. Not every teaching will work for everyone, it has to resonate with you and you need to believe in it. You need to be open-mined at least. The one sentence that was an eye-opener for me was that whatever problem you are having, you can make it ten times worse or ten times better. It depends on how you look at the problem. And that was it for me...
I read several books and each one of them gave me a new tool: for example, The Low of Attraction, that I understood as: we are attracting what we are projecting out. No matter how someone else might perceive this, believe in it or not, everyone could benefit from a positive perspective, finding good in people and situations that are around them. Another example - living in the present moment, again being here and now, not worrying and thinking about tomorrow..You might be overthinking and worrying about an event that might not happen at all, and the only thing you did, you really ruined your "now"...There are many more ideas like this and tools that help to show how to step forward. It is up to each individual to determine what the best fit is for them. There is always room for growth.