Writing a book

I've tried to write stories/stories countless times, but I always seem to loose interest before I actually finish one. The longest page number I got up to was 45 pages or so.

I always put so much detail into the first few pages, making sure to have hidden meanings in the places they visit, in the characters' names... and then I'll gradually loose interest, and move on to another story plot that I only know the beginning, middle, or end of. I have at least 30 Google Docs that just have the first chapter of a story I planned to write but lost interest in.