Two years ago I decided that I needed to switch out my archaic "category" system on this site for a more dynamic "tag" system. Adding categories is a pain, meaning I never have an appropriate one for anything I post. Tags make all sorts of amazing stuff possible. In short, it was a "no brainer," really.
The only problem was that I had a wealth of posts back then, and I didn't look forward to having to go through and tag them all. So I didn't switch over. Because it would be too much work.
It's now been two years and like 600+ posts later, and I actually got around to doing the bulk of the work today. I got it to automatically populate my existing categories into tags, so every post has at least one tag it belongs to, but I've been going through and adding more appropriate tags as I find them. This is a real pain in the butt, but I feel it is well worth it.
The moral of this story? If you think it's going to be too much work to do something now, just imagine how much more work it will be when you actually get around to it.
UPDATE: A lot (most) of my old posts are very poorly titled, so as I go through tagging them I'm trying to fix those as well. This will probably cause them to come through your feed reader again, so I apologize if you've seen them before. Many of you haven't, though, so I don't feel too badly about it.