I had an agent once tell me that writing is the only career where you could legitimately stare out the window for hours and actually be working.
Sad to say, I've used that excuse a time or two too many. ;)
While you can spend hours and days and weeks and months and even years crafting the backbone of your novel or book - fleshing out characterizations, creating a fictional setting, even forming a new fictional culture - eventually, you have to look away from the window and back to the computer. And start the actual writing.
Which might be the hardest part.
I've always said that my least favorite two words to write are "Chapter" and "One." Starting a story has so much pressure - is the opening sentence strong enough? Have I written the correct mix of back-story so the reader knows who the characters are and current action so they don't get bored?
Writing isn't for wimps, guys. Countless hours staring at your computer screen, countless hours sitting there in the same position (that one gets me the most), usually a year of edits and waiting before you see the book in its book form and then a check for waaaaay less than minimum wage. :) If you're in this career for the money, for the job flexibility or for the lack of effort you think you'll need to put into it, you're in the wrong career.
But, if you are reading this post because even though it frustrates you to no end, you just can't resist the pull of those two little words, "chapter" and "one", and all the wonderful possibilities that await for you behind them, then welcome. And please accept our gift of understanding mixed with pity. ;)