In Jon Kabat-Zinn's words:
"every time you come back to yoga practice, you see the effect of not having done it for a while. So in a way you learn more by coming back to it than you would by just keeping it up...Forgetting or neglecting to be mindful can teach you a lot more than just being mindful all the time...Try noticing the difference in how you feel and how you handle stress in periods when you are into the discipline of daily meditation and yoga practice and in period of your life when you are not."
This seems applicable to most skills in life. I've seen it in my violin playing, singing, fitness, and now, mindfulness. I think this point is best illustrated with a personal example, so I apologise in advance if this seems a bit self-indulgent.
Slipping into mindlessness
I have to admit that my holidays were far from mindful. For various reasons, my regular meditation practice had slipped from something like this to something like this. Along with this neglect of formal mindfulness practice, I felt like I had also slipped back into a cloud of unawareness, emotional reactivity, negative emotions, and an auto-pilot lack of consciousness.
I also noticed that I was causing myself a lot of suffering due to the attachments I had; ideas about I had about what holidays or home should be like, or how I should be able to keep up my meditation practice, or even, more deludedly, how other people should be. A commitment to formal mindfulness practice would have helped me to better apply the skills of letting go and letting be in my daily life, and seeing things as they are and not how I would like them to be, which I do better at nowadays than in my pre-mindfulness (mindless?) days.
In a nutshell, due to this lack of awareness, while there were many enjoyable aspects of the break and while I definitely wasn't miserable, I can't say I was flourishing or getting the most out of life, even during a period of near-complete freedom from obligations and commitments.
"It is in the coming back to mindfulness that seeing lies."
While the above may seem a little sobering, there is a bright side to the story. University has started again, and with the structure and momentum of semester, I have begun my regular formal practice again, and am already feeling more grounded, stable and more able to let go (e.g. getting over a burglary in my room relatively quickly).
I've also come back with new ideas about maintaining intention and purpose in my practice. To experiment with the idea of the value of "the coming back", I've decided to try something else to mix up my practice a bit; by practicing six days a week instead of seven. I think that one day off a week will prevent the practice from becoming mechanised and routinised, and leaves something to come back to. For now, I'll aim to meditate for 30 mins in the morning and 10 mins at night from Mon-Friday, take Saturday off, and meditate 1 hour Sunday morning and 1 hour Sunday evening, usually at a group sitting. It might turn out that I prefer to meditate every day, but I'll see how it goes.
Therefore, the key to this seemingly paradoxical statement, "Not Practicing is Practicing" is that not practicing is only practicing if you come back to it, so that you are able to learn something from your time away. More importantly, rather than flagellating oneself over not practicing, or regretting what has already happened, it makes more sense to simply return with a fresh approach, a beginner's mind, and begin again, and again, again, remembering that every moment is a new beginning and the only moment that we are fully alive in.