It's like writing this bog. Every non-trivial post I make (I'm not saying that's a lot of them) is a commitment because: a) I don't like to express opinions about things I don't feel I know enough about (like I just did with the Guardian post). So I often don't post passing thoughts because I feel I need to do more research on the topic, which I don't have time to do. b) Someone might take the time to write me a response, like Justin did, that deserves a reply and possibly a follow-up post and/or research. I'm notoriously bad about replying to my email and, to a certain extent, have gotten over the assumed obligation that just because someone knows how to send me a message I have a commitment to let them take up part of my life. On the other hand, I feel bad about that, because I know from my own experience that it sucks when you send a personal note to someone and they don't reply. And from the selfish perspective, this also effects my reputation and sends a message to the world.
Not to mention what I lose out of the deal, which is perhaps the most rewarding thing about writing a bogthe conversation. Like anything worthwhile, it takes an investment. Sometimes I don't feel I have the time to make that investment. Or, more accurately, other commitments/investments are more important to me at the moment. So I don't. I just kind of go along half-assed, because I feel that's all I have the ability to do for now (i.e., I'm at my wits end trying to keep my life and business and web sites minimally functioning and anything that asks for an additional time investment makes me run hard the other way).
I'm still figuring it out.