We may be desirous of getting on to the path of spirituality for one or more of the following reasons - (1) We may be leading a life of suffering for too long and hence want to see if spirituality can give us "relief." (2) We may be completely weary / bored / disillusioned by the way life has gone on thus far, which feeling may have caused a vacuum to be created in our life. We want to see if spirituality can fill the vacuum. (3) We may be curious about spirituality. We may not be as badly disposed towards life as a person in category 2 above is. But we may be just about bored enough to "try out" something different and think we can look at spirituality. (4) We may be ordained by the Creator to get on to the path of spirituality for His own reasons. (Such cases, in general, would be very rare.) Whatever may be the reason for pursuing a spiritual path, we must leave behind our past baggage of conditioning and open our mind as much as possible to a whole new attitude. Unless one manages to clear his mind of the conditioning received by it thus far, the higher knowledge cannot be accommodated there. It's like a pot filled with mud. Unless and until it is cleared and cleaned of the existing muck, you can't fill it with milk. So, it essentially requires dissolving our limited ego and opening ourselves to the superior identity. Vairaagya (asceticism / detachment) is the cornerstone of spirituality. One has to gradually get out of the perpetual cycle of desires, where the moment one desire is fulfilled, another is ready in the queue. Vairaagya is a complete and true indifference to the physical world. However, vairaagya must arise from within, out of a genuine desire for knowledge of "before and beyond the physical." Vairaagya is not something that should be imposed because then it is counterproductive and unsustainable. Also, such imposed vairaagya is of the kind where one gives up one desire / attachment, only to acquire another. Like the example given in some of the spiritual literature, a man gives up his family and goes to the jungles, but acquires disciples in place of his family and an ashram (cottage) in place of a house and gets attached to them That's no good. The objective of spirituality is to transcend the limited bodily identity and EXPERIENCE the oneness of the single whole that this creation is. Why should, or rather, why does, one pursue spirituality? We can start by saying that one gets a desire to pursue spirituality and hence goes ahead with it. After having reasonably fulfilled many sentient desires, should one not feel at some point that enough is enough? For instance, should one not think that I have been eating spicy food for too long, let me stop now? What is the point in going on doing the same thing over and over again or desiring more and more of the same thing all through one's life till one dies? Shouldn't one realize at some point that there may be something preceding and succeeding life, beyond what we experience through the five senses and build up as our ego and occupy our consciousness with all the time? Now about the "who" part. The good deeds leading to accumulation of spiritual credit are like a walk towards the gate to the ultimate destination. However, to actually get the ultimate experience, one has to enter inside through the gate. Now, it is here that there is an element of divine grace that comes in and only a few in accordance with the sovereign scheme of the Creator will get the chance to enter. The reason to bring in the aspect of divine grace is that we do not know how the selection is made, nor can it be understood. That is why even Jesus Christ said in the Bible (Mathew 7:13-14) that the gate is narrow and many will jostle to enter; but only a few will manage to get in. However, a seeker desirous of attaining the ultimate goal must put in his best efforts by way of the prescribed spiritual practice. That is the only thing within his capacity.