Best made plans kaput

I had big plans for my vacation in October. I was off, but wasn't going anywhere. My family came for a visit, so once I'd pushed the six of them out of the door, I was free!!!
But no sooner had I put down the Playstation consol, I got a sore throat. The next day I woke up feeling run down, tired and just plain wussy. Then when I went back to the newsroom and had to work seven days straight.
My plan was to spend my vacation writing my book.
Yes, yes, I'm a cliche. I'm writing a book. But it's not about journalism or based in a newsroom.
It's a young adult book in the fantasy/science fiction realm.
I think the premise is awesome, but it's hard writing a book. I'm not a huge fan on writing as it is. I do it partly for a living and it's hard. But for a hobby? Sometimes I think I'm nuts.
I've asked my hubbie a ton of times whether I'm the biggest idiot spending hours and hours and hours writing a book that probably won't get published.
Of course, this is the millionth book I've started. I do have quite the stacked drawer of partly finished manuscripts. I promised myself by the time I turn 40 next summer I will run another marathon, lose 20 pounds (I'm a fat runner) and finish this book.
It's part of a triology. I know another cliche. But my idea cannot get finished in one book. It's possible to wrap it up in two, but not really.