Tuning into the sensations in the body is the first foundation of mindfulness. This is a crucial practice because normally whatever we experience — our feelings, emotions, thoughts and perceptions — also arise as sensations in our body.  It is also the case that previous experiences – good and bad – can be stored almost in the cells of the body, and can be a better signal of what is going on than our interpretation of it. When we practice mindfulness of the body, we train in being open to a changing stream of sensations without pushing away or holding on, and this practice becomes our refuge when faced with emotional storms.

The teaching  of the actual body is the harbour and the weir.

This is the most important thing in the world.

Dogen

There is one thing that, when cultivated and regularly practiced, leads to  peace, to mindfulness and clear comprehension, to vision and knowledge, to a happy life here and now, and to the culmination of wisdom and awakening.  And what is that one thing? It is mindfulness centered on the body. 

The Buddha, Anguttara Nikaya