I wrote my first novel when I was 15, and I can guarantee I was serious about my writing back then. I wanted a career of it, hoped I could pay my way through college with writing, would have a big bestseller before I was eighteen. You know, the normal things a teenager assumes.
I had Writers Market books and had picked out which publishers I would send my books too, and so on. Mostly insecurity kept me from ever really trying. The few times I'd submitted anything, I'd failed to get very far (and generally the friends I entered with were accepted, which reinforced my idea that I wasn't very good). I was terrified of sending out my book, revised it something like 9 times (and it still sucks lol), and tried to learn what I could and get brave enough to try it.
I went to college and grad school right out of that, though, and that cut so severely into my writing time that I didn't really get the opportunity. On top of that, one of my writing professors had said that while I was a great writer, he wasn't sure if I knew how to tell a story, which basically left me heartbroken. I was convinced I couldn't write, that I would never be able to, and that I just didn't have the natural talent to pull off a career.
I started writing silly things in grad school again, a couple of fanfics, that sort of thing, just to play around. Those were safe, in a way, because I wasn't doing anything with them, wasn't going to submit them, wasn't posting them online. I actually started to notice I was improving in certain areas. I was learning a bit more about story from a good friend I wrote with, and my dialogue was actually getting decent, and overall I was starting to feel more confident.
A couple of years later, I had a dream that I woke up from and just knew I had to write. The main character was too amazing, and I loved the concept, and I thought it would make a great story. So I thought back to what my professor had told me and realized that if plot was my weakness, I was going to have to learn a way to get around that. I started outlining, and it made a huge difference. I worked on that book for a little over a year, and when I was finished I
knew I had to try to have it published.
That one didn't get me an agent, but the next one did, and I learned so much not only from that one book and actively trying to improve my weaknesses, but also from this site and the other blogs and industry information on the internet.
So I guess the moral of my story is that I always knew what I wanted, but lack of confidence always kept me from it more than anything, and the most important element of becoming a better writer is to not get discouraged by criticism, but to look at it objectively and recognize it for what it is: a way to help you improve.
ETA: I don't have kids yet, but I'm anticipating having to scale back once I do. Babies especially require so much energy and time that it's hard to imagine stressing myself out to get a book done with an infant.