Alan Wallace Fall 2012 Retreat Podcast: Vipashyana, Four Applications Of Mindfulness

Meditation: mindfulness of breathing at the nostril. Focus mental awareness on breath coming in and out at the nostril or upper lip, wherever you feel the sensation most clearly. Engage with the full course of in and out breath, arousing attention at in breath and releasing thoughts and relaxing at out breath. Experiment with staccato counting to counter rumination.
This practice enhances vividness, but does so without sacrificing stability and relaxation. 
Be relentless about breaking up rumination by resting engaged! Meditation starts at 1:40