Creating your own self improvement book is a great way to look at your life.
You are unique and therefor your journey through life is unique. This make you the one person qualified to create a self improvement book for yourself.
If you live your life as a learning journey and document what you learn then at the end of your life you will have the perfect self help book for your.
With the billions of people in the world, there will be a few people out there on a similar journey. Imagine what they can learn from your life expereinces, epiphanies, and ways of dealing wiwth different situations.
Your story and your voice are valuable.