Writing a book is one of the most joyous things that a human being can experience! I know because I have written a few books and published two. They say that the closest a man can come to experience childbirth is writing a book. The feeling of creating a written piece of art that can be shared with the world is great.
Whether one writes fiction or non-fiction, the process is similar. Every writer has their own way of doing things, but I personally feel that an outline should be used to create a proper structure to your book whether it is fiction or non-fiction. When you create an outline for the plot or an outline for the main chapters of a book, it is easier to write it.
One piece of advice to budding writers who may struggle with the idea of writing a book with many pages in it. Don't think of it as writing a 365 page book, think of writing 1 page everyday for one year. That sounds a lot more achievable doesn't it? As in everything in life, be it exercising, dieting, investing, etc. It is consistency that counts. When you do a little a day, everyday, you will always get a better result. This is because the mind handles small tasks better even if they are many of them. If the mind perceives something as a large Herculean task, it tends to get scared or overwhelmed! So remember, don't overwhelm yourself. Perform smaller tasks on a regular basis for better results. Good luck!
