Only the quest "Who am I?" is necessary.

Maharshi: Moksha is to know that you were not born. "Be still and know that I am God." To be still is not to think. Know, and not think, is the word.

D.: There are said to be six organs of different colours in the chest , of which the heart is said to be two finger-breadths to the right of the middle line. But the Heart is also formless. Should we then imagine it to have a shape and meditate on it?

Maharshi: No. Only the quest "Who am I??" is necessary. What remains all through deep sleep and waking is the same. But in waking there is unhappiness and the effort to remove it. Asked who wakes up from sleep you say `I'. Now you are told to hold fast to this `I'. If it is done the eternal Being will reveal Itself. Investigation of `I' is the point and not meditation on the heart-centre. There is nothing like within or without. Both mean either the same thing or nothing. Of course there is also the practice of meditation on the heart- centre. It is only a practice and not investigation. Only the one who meditates on the heart can remain aware when the mind ceases to be active and remains still; whereas those who meditate on other centres cannot be so aware but infer that the mind was still only after it becomes again active.

from Talk 131, Talks with Ramana Maharshi http://talks-with-ramana-maharshi.blogspot.com/2007/08/talk-131.html