We've talked about Seinfeld's "Don't Break the Chain" method of forming habits, but if you can't fully complete the goal each day, at least do something rather than having a "zero day".
Photo by darylljann.
Limitless, reporting on a Reddit thread, calls a zero day a day in which you did nothing towards your goal. For example, you have a goal of doing 50 push ups a day and haven't done any so far. You can avoid breaking the chain by doing just a few. Once you get started you may actually meet your goal!
Even if you don't meet your minimum goal for the day, making sure you don't have a Zero Day may prevent you from Breaking the Chain.
No More Zero Days [Be Limitless]