As I've gotten older, I've found that I crave more and more alone time. I work so hard during the week, and have a lot of other obligations to keep up with, and I find that in my free time, all I want to to is sit at home and read or watch a movie, or go work out and de-compress. I don't want to alienate my friends, who are still very important for me, but I find that more and more often I'm making excuses when somebody asks if I want to hang out. Is this a problem? Or does this tend to happen as you get older...and should I just let myself feel OK about it?