The essence of Guru Yoga

Dilgo Khyentse Rinpoche

(from "Guru Yoga"):

The essence of Guru Yoga is simply to remember the guru at all times: when you are happy, think of the guru; when you are sad, think of the guru; when you meet favorable circumstances, be grateful to the guru; and when you meet obstacles, pray to the guru, and rely on him alone. 

When you are sitting, think of the guru above your head. When you are walking, imagine that he is above your right shoulder, as if you were circumambulating him. When you are eating food, visualize the guru at your throat center and offer him the first portion. Whenever you wear new clothes, first offer them to the guru, and then wear them as if he had given them back to you.

In brief, and to conclude, Guru Yoga is the essence of all practices and the easiest on which to meditate. It entails no danger and it is endowed with boundless blessings. It has been the main object of practice of all the enlightened beings of India and Tibet, and in all the different schools. 

Through the Guru Yoga practice, all obstacles can be removed and all blessings received. And through merging our mind with the mind of the guru, and remaining in the state of inseparable union, the absolute nature will be realized. This is why we should always treasure Guru Yoga and keep it as our foremost practice.