I don't know that I have anything to contribute on the "meaning of life" front, but I have been doing some reading for the day job that might help address the "I have no interests/hobbies" question (which may solve the bigger issue.)
I am reading some research by educational psychologists about the process of going from a "passing interest" to a "serious passion" and why this happens with some interests but not others. They argue that people typically go through four stages, beginning with having their attention caught, to spending more time with the interest but still needing a lot of help and support to pursue it, to being able to pursue it more independently, to being an expert. (I am seriously paraphrasing 150 pages of dense text, so please forgive). My guess with a lot of people who don't feel like they have interests is that they never transition from stage one to stage two, or they play around in stage two a bit but never move through it. (The research also says that it's easy for things to go off the rails here.) It's not until stage three that people would usually identify themselves as having X as a hobby. So one thing you might try--when something catches your eye, try more specifically to make plans to pursue it, even if you have to push back against your inner introvert to take a class or join a group. You can go back to being your independent introverted self once you're a little better at whatever it is! Or if one thing doesn't work out--the guitar teacher turns out to be a bust, for instance--make a deal with yourself that you'll try three approaches before you decide the guitar isn't for you. (If you really never find anything interesting, you should check with your doctor. Humans are hardwired to look for and enjoy finding interesting things, and not doing that may indicate brain chemistry issues. But I am guessing that is not the case here.)
The other thing is to ask yourself if you really have no interests or hobbies, or if they just aren't something you are willing to admit to yourself/on the MMM boards. I mean, watching television or following a sports team or eating out can be a hobby, even if it's not considered by society or these boards to be a "good" hobby, and take up substantial time which would explain why it's hard to get started with something else. The research I was reading also made the point that people typically have 4-5 interests at a time, but these could also be professional or family-based (ie, researching child-rearing advice, or how to assist a special-needs child) so if you have a few slots already taken, there's less room for the "fun" ones. Anyway, all food for thought...
