If you are someone on a mission you should have been writing on your subject in your WordPress Blog, or even on Hubpages or Bubblews. These writings will have a theme of course (this could be anything from abseiling to zen gardens) and these themed writings could easily be assembled into a relevant eBook.
The writing will also have active links which will make it interesting for the reader who is also a fan of your subject. The writing / editing process will be much easier since most of the work has been done. Sometimes you will need to writing extra paragraphs linking chapters together so that there is a nice flow.
One of the plusses in making an ebook is that sites like Bubblews and Hubpages do not check ebooks for copyright infringement so you may refer to your book without the risk of it being blocked for this reason.
We at Kima Global can help you to make and distribute your ebook. We will design an eye catching cover for you as well so that your book can get noticed.
Why not have a look through your old blog posts to see if you have enough for an eBook. Bear in mind that eBooks need a smaller word count than a conventional paper book.