Inhaling deeply and retaining the breath may initially prove difficult for some. Do the best you comfortably can. Self torture games of any kind are to be avoided.
For those who experience no discomfort, inhale and release the breath slowly, once or twice, to the mental count of eight to one, thus: “eight..Seven...Going down, deeper... six …five…deeper… four, three, two, one…zero, zero, zero.” As you count down with the eyes closed, becoming more and more relaxed, press the tips of the index finger and thumb of each hand gently together as you mentally repeat “zero”, adding “relax…serenity” or whatever keywords you prefer.
As you inhale you may occasionally find it helpful to tense the fists and relax them as you slowly exhale.