Meditation on the greatest mantra that's already within our breath, So Hum. Then meditating on a variation...
Hum...Sa. So....Hum, So Hum...Hum Sa,
So...Hum Hum Sa, Hum...Sa, So...Hum

The Witness is the highest form of meditation because it is "seedless," or, with an object of concentration. You sit and observe the thoughts and emotions.