I can't really use the excuse of not having something to say, as when I don't feel my day to day is worth writing about, I can think up a topic to write a few words on. Free time is not that much of an issue, if I have time read others people's journals, then that is time I can make small comments or posts. You could say that while I may have the means and opportunity, I probably don't have the motivation.
There may also be a case of 'the longer you leave a task, the harder it is to do', and it feels easier just to not say anything much, the times I might have said something being overruled by the habit of keeping quiet.
Anyway, just a few lines as a friend wanted me to post more (not a nudge but a snug), so here I am in October.