If 'attention' is the oil in the lamp of consciousness, then 'sensation' is the warmth produced by the lamp.
In one respect, following a spiritual discipline - that is, actively employing inner exercises towards a definite direction or objective - has a unique application. It is an instrument to channel specific qualities of energies at the appropriate time to support Soul creation.
Spiritual discipline is like a gardener who waters the garden - the exercise of watering must nourish the plants instead of the weeds, otherwise, much water gets wasted and the garden can become overgrown.
Without a spiritual discipline, the energies scatter as they are open to the disruptive influences from outside, and can only find their place by chance or accident.
The measure of maturity or responsiblity (literally, the 'ability to respond') is the practical undersanding of channeling energies.
When I consciously direct the intellecutal attention to engage with the sensations of the body, this action automatically causes a change in my State of Being - I AM more whole, more alive, more receptive to the impressions that are constantly pouring in. In a sense, I am channeling one quality of energy to blend with another, that naturally gives rise to a healthy third quality. This is true alchemy.
When I see the workings of my own energies, and a maturity in channeling them when needed, then I can begin to 'see' the corresponding workings of other people's energies and the ability to help them channel theirs.
Spiritual discipline is much more than a passing fancy or part of a daily regime, it is the foundation of self-evolution that calls to itself the intelligence of a very different order.
In a boat trying to navigate the sea of life, one must rely on the power of God's wind - but in order to do this, one must first raise their own sails.