Here is a suggested meditation from “Living Fully – Finding Joy in Every Breath” by Shyalpa Tenzin Rinpoche p. 145-6:

Breathing Meditation: Hello and Goodbye

Sit with your back erect and look straight ahead with your eyes wide open.  Inhale and exhale.  Do not force your breathing or try to modify it in any way.  Do not think of yourself as the one who inhales or exhales.  Just be with your breath, naturally and sincerely.

Recognize and watch your breath.  When you inhale, recognize the inhalation, and when you exhale, recognize the exhalation.  Be present in the breath.  When inhaling, welcome the breath by saying silently in your mind, “Hello.”  When exhaling, bid farewell to the breath by saying, “Goodbye.”

With every inhalation and exhalation, repeat, “Hello, goodbye, hello, goodbye.”  In this practice, you are neither accepting nor rejecting what comes and goes.  When the breath comes in, you welcome it with awareness: when the breath goes out, you bid farewell by mindfully letting it go.  Try not to miss a single inhalation or exhalation.  When you do this practice, do not let anything distract you.  Maintain fresh awareness of your breath.

You might be wondering, What is the purpose of saying, “Hello and goodbye.”  Actually, this practice has no purpose.  The practice of hello and goodbye has always been our natural way, but at some point we were diverted.  We became lost and bewildered, and frustration and suffering grew.

To be free of confusion and suffering, we have to return to our primary purpose, which is this practice of hello and goodbye.  Hello and goodbye is all we need.  We accumulate so many things, but the more we accumulate, the more we suffer.  There is no good reason for collecting so many things.  Embrace the way that has existed from time immemorial, which is to say, “Hello and goodbye.”  There is no need to worry, even if you recently got divorced or lost your job.  You no longer have to dwell on these things because your practice is simply to say, “Hello and goodbye.”

This practice allows you to simply be yourself and see reality just as it is.  You recognize your essence when you say, “Hello.”  Your essence is like space; it is wide open and easily accommodates your thoughts, feelings, and perceptions.  Like a vast ocean, you welcome everything that swims through your open expanse.

You acknowledge your unobstructed nature when you say, “Goodbye.”  Appearances arise without beginning or end, but you cannot grasp or hold onto any aspect of this unceasing display.  You cheerfully bid farewell to every passing appearance.

It is like watching beautiful bubble arising from water.  You welcome it with, “Hello.”  Immediately the bubble bursts, and as it does, you say, “Goodbye.”  There is no anticipation because you are not looking forward and no regret because you are not looking back.  Without any reference to past or future, there is only the eternal present — and that is to say, “Hello and goodbye.”