Once again, if your mind has wandered, come back to this sensation of breathing.
"Coming back" to the meditation object is one of the two skills required for the stage of concentration meditation:
Steering is the ability to direct the mind, or to re-direct it when the mind has wandered. This is usually compared to driving a car. One will never drive in a perfectly straight line, but one will redirect the steering wheel as soon as one notices a deviation from the intended track, lane or direction. Steering is sometimes also called "placement" (L. T. Namgyal & Rinpoche, 2011, p31) - attention is placed upon an intended object.
Staying is the ability to remain focused on the meditation object for as long as desired or possible. This could be measured in percent of the time one does concentration meditation.
Both abilities require meta-cognitive introspective awareness, which is the ability to monitor, in real-time, the state of one´s mind regarding concentration.
Namgyal, L. T., & Rinpoche, K. T. (2011). The Ninth Karmapa’s Ocean of Definitive Meaning (New ed). Snow Lion.