Will anybody be interested to read a biography?
Instead include 20 case studies of 20 people discussing how they got where they are today. These could be 20 chapters of your book.
You can interview these people either live or over Skype.
Find out what their dreams and challenges were. How they overcame them. Find a common theme between them that ties into the theme of your book.
Or maybe each chapter could discuss a different version of your theme. Like a different step.
Start and end with the most colorful ones. Don’t forget to finish each story with a twist. Something that your reader wouldn’t expect. This will help them turn the pages.
Start each chapter with crazy story. Something like, “During our interview his chair broke and he banged his head against the floor. There was blood everywhere. Then we became friends for life.”
Oh, and by the way, include your story too.
Actually, you can write a story about your experiences with your theme and further illustrate with those case studies.
Hope this helps.