Nowadays this meditation is often referred to as the body scan. The goal, however, is not merely relaxation or even falling asleep, though it can also be used for that purpose. It is actually about consciously being present in our bodies at all times. Also after your meditation session or your mindfulness training. The conscious experience of the constantly changing sensations (pleasant – unpleasant) can help us to observe our unconscious reactivity: fight or flight. 
During this meditation you will notice that your thinking activity decreases. The energy needed for this is no longer centered in your head; now this energy flows evenly throughout your body. Hence the extremely pleasant, spacious feeling.
This alert and allowing state of being is often referred to as “presence” or “the receptive mode”. And of course this can only take place in the timeless NOW.

“The key is to be in a state of permanent connectedness with your inner body, to feel it at all times.
This will rapidly deepen and transform your life.”
(Eckhart Tolle)

This meditation is very similar to Vipassana, which means: clear insight, seeing things as they really are. The body is not rejected, but it becomes a doorway to the deeper Truth behind our visible reality.
By repeating this meditation regularly, we experience that we are vibrational beings and we dissolve resistance time and again. In this way we raise our frequency and we consciously align ourselves with the Higher Self or our Inner Being. In addition, it is conducive to the health of our physical body.

“The more consciousness you bring into  the body, the stronger the immune system becomes. It is as if every cell awakens and rejoices. The body loves your attention. It is also a potent form of self healing.”
(Eckhart Tolle)

I do not consider body awareness as an isolated technique, but as a way of life. No extensive courses are required, because with this meditation it is simple and practical, based on your own direct experience.

Videos/guided meditations for Body Awareness in several languages, can be found on my YouTube-page.
Here’s one in English: Relax & Align (first part of Releasing Pain and Suffering Meditation).