People over-commit all the time. Whether they know it or not, most people are optimistic about the things they think they can do, especially if it is something they've been doing for a long time. I think new years resolutions are for people who wish they were motivated (like me [which is why I don't set these types of things]). The beginning of the year always makes me feel like I am going to get things done, though. I guess people just need to start doing and stop thinking about doing, but it is not always that easy.