Why do we do Prostrations?
First of all, we should know why we do prostrations. We do not do them to endear ourselves to somebody else. We do not do them for the Buddha. Such concepts are completely wrong. The Buddha is not a god of this world. We bow down to purify all situations from the past where we did not respect others. Being interested in our own satisfaction and ourselves we did many negative actions. Prostrations help us realise that there is something more meaningful than ourselves. In this way we purify the pride that we have accumulated through countless lifetimes thinking, "I am right," "I am better than others," or "I am the most important one." During countless lifetimes we have developed pride that is the cause of our actions and have accumulated the karma that is a source of our suffering and problems. The goal of prostrations is to purify this karma and to change our mindset. Prostrations help us rely on something more meaningful than our pride and ego clinging. In this way, through full confidence and devotion, we get rid of everything we have gathered because of pride.
When we do prostrations we act on the level of body, speech, and mind. The result of doing them is a very powerful and thorough purification. This practice dissolves all impurities, regardless of their kind, because they were all accumulated through our body, speech, and mind. Prostrations purify on all three levels. Through the physical aspect of prostrating we purify our body. We offer our body to the Three Jewels (Buddha, Dharma, Sangha) and to all sentient beings, wishing that all their wishes are fulfilled. Through the repetition of the refuge mantra and the meaning we ascribe to it, we purify our speech. Through confidence in the Three Jewels we develop enlightened attitude and devotion. As we are aware of the perfect qualities of the Refuge and offer everything to it, the veils in our minds dissolve.
When we do prostrations we should understand that good actions are the source of happiness of all sentient beings. Prostrations are a good example of this fact. When we do the practice using our body, speech, and mind, we offer our energy to others wishing that it brings them happiness. We should be happy about this fact and do prostrations with joy. (Source: Lama Gendyn Rinpoche on Prostrations)