Writing is a very solitary profession.  It's not easy going into my office alone day in and day, with no one to talk to but my cat.  Writing does not require verbal communication or collaboration with others.  It requires you to do the work by yourself for months at a time and then hope the end product is good enough to be appreciated by others.  I'm lucky enough to work at home alongside my husband, so I'm not completely devoid of human contact all day.  But as we are both in our little worlds plugging away at our projects, we do not actually interact.  Don't get me wrong.  I love what I do.  But after a certain amount of time, I begin to feel like I'm isolated from the world and living in a cave.  That's when venturing outside the house to work can do wonders.  However, that only takes care of the isolation, not the interaction issue.  Or the lack of feedback and annoying self-doubt.  It's easy to fall prey to worries that you don't know what you're doing.  It takes a certain amount of self-discipline and self-determination to get through those moments.  (As well as a bit of wheedling reassurance that you are not in fact doomed to failure from your husband and friends.)  Writing and other solitary professions are not for the faint-hearted, which is something I wish someone had told me years ago.