A very important aspect of meditation is developing awareness, mindfulness. So here we can use our breath to develop awareness. In Pali this technique is called Anapanasati, developing awareness, mindfulness, in relation to the in-breath and the out-breath. We can use the breath to develop the practice of mindfulness and awareness because we are breathing all the time and the breath is with us all the time. Ajahn Chah, one of the meditation masters in Thailand, has said that if you have time to breathe, then you have time to meditate. So this is the first point why the Buddha might have chosen breathing as a technique for meditation.