In the chapter "How Long to Practice?" of Wherever You Go, There You Are Jon Kabat-Zinn talks about the magic of the moment and the value of even a glimpse of awareness:
For those seeking balance in their lives, a certain flexibility of approach is not only helpful, it is essential. It is important to know that meditation has little to do with clock time. Five minutes of formal practice can be as profound or more so than forty-five minutes. The sincerity of your effort matters far more than elapsed time, since we are really talking about stepping out of minutes and hours into moments, which are truly dimensionless and therefore infinite. So, if you have some motivation to practice even a little, that is what is important. Mindfulness needs to be kindled and nurtured, protected from the winds of a busy life or a restless and tormented mind, just as a small flame needs to be sheltered from strong gusts of air.
If you can only manage five minutes, or even one minute of mindfulness at first, that is truly wonderful. It means you have already remembered the value of stopping, of shifting even momentarily from doing to being.