Past is what has already ceased to exist; future is what is still to be born; only the present exists, and is, therefore, real. The memories of the codes recorded in the past are translated to become tormenting mental states for the future. Refuge in the present alone spares one from the ordeal of the memories of the past and the tortures of the future. This is because memories, etc., are liable to produce the contamination of attachment and aversion. The perception of the present alone could be impartial.
Mind becomes agitated when the physical behaviour is not in harmony with the mental state. And the mental agitation creates hurdles in the practice of self-discipline.
Bhava-kriya,, i.e. synchrony of the mental state with the physical behaviour is in itself a discipline, and steadies the mind, bringing it to meditational level. For example, when one walks, his mind should be completely occupied and be totally aware of the action of walking and it should not be engaged in other perceptual or conceptual activity of any sort. Only then the act of walking is qualified to be bhava-kriya. Though our sensory out-posts would continue to send innumerable signals to the brain through the sensory nerves of vision, audition, etc., the sadhaka should remain indifferent to them, and keep his mental function fully engaged in walking. When the mind is fully associated with the vocal and physical activities, they become not only more efficient, but also more purposeful, because the power of the psyche itself is inherent in them. Then and then alone, the activity is bhava-kriya.