No matter what the habit is, it'll be a lot easier to implicate if you break it down into smaller sections and build up from there.
For example, if your new habit is to eat healthy, your first step could be to eat one healthy breakfast meal each day. Then, once you've mastered that step, start eating a healthy lunch, then dinner, then snacks, etc.
If you try to make a radical change in your life, it will be difficult and unpleasant and has a higher chance of failing. Break your habit down into smaller steps and work on one small goal at a time. Eventually they will all add up to the new habit you wanted to start.