Officially, Broken Windows theory refers to a behavioral pattern on a societal level, where environments that tolerate little 'glitches', like a broken window or uncollected litter, will tend to slide towards the direction of more and more glitches. Throwing a piece of trash on the floor is perceived as a worse offense when the streets are trash free, yet it can be perceived as barely an offense at all when the streets are filthy. This is, in part, a mental bias: The action done is the same (throwing trash in public space), the end result is the same (an equal amount of trash is added to the environment), but we perceive the severity entirely different.
On a personal level, I find that a very similar mental bias is at work. When some aspect of your personal life is well maintained, small glitches are perceived far more severely than equal glitches on a less maintained aspect. Let's say you're working out and in top physical shape: Missing a workout day will feel a far worse offense than if you were out of shape and working out very sporadically. Something in our natural assessment of the severity of glitches is off: We either perceive a glitch as far more severe than it actually is, or we perceive a glitch as completely insignificant. In reality, we are usually wrong on both extremes.
On a societal level, cities and organizations can leverage the bias by reducing tolerance to glitches on purpose. Citizens don't need to be aware of the idea of broken windows; they just need to experience a broken windows-free environment for the bias to keep them in line. On a personal level, keeping a broken windows-free environment in every important aspect of our lives is simply not a viable long term solution. We will eventually slip up, and when we do, the negative side of the bias will kick in and can turn a small slip into a crisis.
As individuals, however, we can do something that can't be done on the societal level: We can choose to recognize and overcome the bias, by consciously adjusting our gut response to a glitch according to where it falls on the broken windows spectrum. In the above example, if we are the top-shape person missing a workout, the adjustment is to not beat ourselves up about it and simply make sure we don't miss the next one, without letting the glitch affect our mood or self perception more than it should. The other end of the spectrum, which is the more interesting adjustment to make, is the one where we are the out of shape guy, who doesn't see much difference between not working out 364 days a year compared to not working out 365.
Both of these adjustments require a conscious override on a subconscious process (a subject that deserves its own discussion, but on which I've touched briefly in the past, when dealing with the subject of feeling overwhelmed).
The adjustment of increasing the severity of glitches we usually wave off can be a subtly powerful behavioral modification. One area in which I've acutely experienced it is in maintaining my apartment's cleanliness. I'm by no means a clean freak, and my living environment's natural state is never pristine. When some breach of cleanliness enters my field of vision, like a visible piece of dirt, clothing on the floor, or some magazine under the couch, my initial gut reaction is to keep it out of my conscious by dismissing it as not a big of a deal, and the empty promise of "I'll clean it up on the weekend".
I've noticed that in periods when I let these glitches escalate a bit and I tell myself, "just spend a second and deal with it", the natural cleanliness state of my apartment is significantly increased. I'm by no means living in a broken windows free environment, but my environment's tendency to slide into chaos is significantly reduced, as a direct result of me taking small daily actions that my gut tells me are insignificant.
This can easily be applied to many fields in your personal life: Personal hygiene, social life, work, diet, personal projects, or what have you. The trick is to capture that moment of assessing a perceived glitch as insignificant, and consciously overriding that assessment.
Since the conscious override can be exhausting, and since it takes takes time and persistence to achieve long term behavioral modification, my recommendation is to pick one specific area in your life which you want to improve on and apply that behavioral modification to it.