From the end of Chapter 7 ("What to Do with Your Mind") of Mindfulness in Plain English by Bhante Henepola Gunaratana:

Don't set goals for yourself that are too high to reach. Be gentle with yourself. You are trying to follow your own breathing continuously and without a break. That sounds easy enough, so you will have a tendency at the outset to push yourself to be scrupulous and exacting. This is unrealistic. Take time in small units instead. At the beginning of an inhalation, make the resolve to follow the breath just for the period of that one inhalation. Even this is not so easy, but at least it can be done. Then, at the start of the exhalation, resolve to follow the breath just for that one exhalation, all the way through. You will still fail repeatedly, but keep at it.

Every time you stumble, start over. Take it one breath at a time. This is the level of the game where you can actually win. Stick at it — fresh resolve with every breath cycle, tiny units of time. Observe each breath with care and precision, taking it one split second on top of another, with fresh resolve piled one on top of the other. In this way, continuous and unbroken awareness will eventually result.

Mindfulness of breathing is a present-time awareness. When you are doing it properly, you are aware only of what is occurring in the present. You don't look back and you don't look forward. You forget about the last breath, and you don't anticipate the next one. When the inhalation is just beginning, you don't look ahead to the end of that inhalation. You don't skip forward to the exhalation which is to follow. You stay right there with what is actually taking place. The inhalation is beginning, and that's what you pay attention to; that and nothing else.

This meditation is a process of retraining the mind. The state you are aiming for is one in which you are totally aware of everything that is happening in your own perceptual universe, exactly the way it happens, exactly when it is happening; total, unbroken awareness in the present time. This is an incredibly high goal, and not to be reached all at once. It takes practice, so we start small. We start by becoming totally aware of one small unit of time, just one single inhalation. And, when you succeed, you are on your way to a whole new experience of life.

(cf. Being Nobody, Going Nowhere (2008-10-18), No Method (2010-01-21), Without Effort, Analysis, or Expectation (2010-08-04), Goals and Failure (2014-12-13), Now and Here (2015-06-07), Mantra - No Goals (2015-07-27), Aspire without Attachment (2015-12-28), ...) - ^z - 2016-06-08