I'm doing an experiment this month, regarding my sugar intake. I'm going to stop eating dessert at work lunches, and stop eating sugary afternoon snacks. Outside of work, this sort of stuff will still be fair game, but this should cut out the bulk of my non-healthy food intake without making me go entirely cold turkey. The main reason I'm doing this I think is because my sweet tooth has a fairly dominant personality, and once in a while needs to be reminded who's boss. Recently I've been finding myself eating sugary snacks even when I didn't really want or need them, so I'm just going to try out some other habits for a while. After a month, I'll see if I feel any different as a result, and decide how to continue.
This all got me thinking about the more general idea of resolutions. Making new year's resolutions is a pretty well known concept, but I think that getting in the habit of making new month's resolutions could be even more effective. It's less intimidating to think of doing something for a month rather than for a year, and you can focus on it more intensely. It will help you work on self-improvement throughout the year (if you're the type to forget your new year's resolutions by February). It allows for more experimentation/turnover with different things you want to add to your life.
I can think of lots of ways I could use a habit like this in my life, aside from the current diet issue. For instance, one month I might decide to draw something every day. I'd love to start drawing again but it's hard to do it much when I'm not in practice. After a month of making myself do a little bit every day (whether I "feel like it" or not) I'd be more in practice, and I'd be comfortable with just drawing more in general, even if I don't continue to do so every single day. And I'd be more comfortable taking time away from, say, music to spend on this, if I know it's just this month's focus and I'll have more time for music later. Similarly with other possible resolutions (e.g. being nicer to people, keeping your home cleaner, meditating every day, or whatever else people resolve to do) focusing on it for a month will help you determine how to incorporate it into your life on a more permanent basis.
I don't generally make/keep new year's resolutions (except this one) but I could probably get into the monthly thing more. We'll see.