First religions, then later spiritual systems, always demand effort of some kind - but the nature of effort could be very different - maybe these could be termed relaxation versus concentration; which corresponds approximately to contemplation versus imagination.
At various times in my life I tried to follow both of these distinct paths - of "opening" versus "closing" the mind.
However, the distinction between these is blurred by the potential difference between means and ends; because there is often an implicit assumptions that we can or should pursue one kind of end by a training of another kind - whereby the means is distinct from the end.
My assumptions is that originally the means and ends were identical - that an immersive and contemplative spirituality (such as that of our nomadic tribal ancestors, and still of young children) is something that people Just Do - means and ends are identical.
But when religion became established; it became usual to pursue contemplative spiritual ends by means of rigorous, prolonged, and intensive training that was not - of itself - contemplative and spiritual.
In summary, a personal would learn a symbolic and ritual system, would learn its proper meanings and responses - and by effort, concentration, and repetition would learn to experience the desired subjective and imaginative responses.
The goal is that an individual learns develops a new kind of spontaneity - so there is an element of paradox, or even contradiction in the fact that the means are often dry and mundane, while the end-point aimed-at is transcendent.
This is the nature of traditional religion even at its best and highest; there is a necessary alienation and functionality and mechanical experience; that is "sacrificed" in order that for each individual at some times and places - or, a minority of people for most of the time - there can be a spiritual participation with the divine.
Thus we "pay" for the spiritual, with the secular - as individuals, and socially (e.g. several peasants mundane labour pays for each monk's spiritual experience).
I have a strong intuition that the future of spiritual effort is one in which we return to the primal situation in which means and ends are again identical; in which what we need to do here-and-now, is exactly the same as what we are aiming to do in future.