I firmly believe, being a parent of 12 years, that writing and parenting have a lot in common. There are things no one tells you about, and things everyone tells you about. Unfortunately, some of the most important things are the ones you aren't told about, or which are glossed over, or which they couldn't tell you about it they wanted to.
For writers, it seems that no one can really tell you about the process of writing--how many hours a day you'll need, how much energy, how many rewrites, how many letters or conference meetings with agents and publishers it will take. Those things are so individual, and some so serendipitous that only God knows what your process will be. After that 10th book, you may have a better idea.
Both parents and writers face the question of whether what we are doing is the best thing. We grapple with insecurities about the depth of our commitment, and we spend a lot of time in the middle of the night dealing with issues. Well, I say "we" and I mean "I" do. If I awaken in the night and my thoughts turn to my novel, I start reworking scenes, or creating new ones, or asking myself if I can make the book deeper and more meaningful, instead of just entertaining. As a parent, I ask myself many of the same questions about the way I'm relating to my daughter--am I paying enough attention? Am I giving her enough depth, instead of just entertaining her?
Writing and parenting--two worlds of insecurity. So when someone goes on and on about how the book just "flowed" out of them, maybe you need to pick up a mental shovel.