Ajahn Chah

The river that must flow down the gradient is like your body.

Having been young, your body's become old and is meandering.

towards its death don't go wishing it were otherwise it's not something you have the power to remedy the Buddha told us to see the way things are and then let go of our clinging to them

Take this feeling of letting go as your refuge.

Keep meditating even if you feel tired and exhausted.

Let your mind be with the breath.

Take a few deep breaths and then establish the attention on the breath using the mantra word BUDDHO.

Make this practice continual.

The more exhausted you feel, the more subtle and focused your concentration must be so that you can cope with any painful sensations that arise.

When you start to feel fatigue,

Then bring all your thinking to a halt.

Let the mind gather itself together and then turn to knowing the breath.

Just keep up the inner recitation.

Let go of all your externals.

Don't go grasping at thoughts of your children and relatives.

Don't grasp at anything whatsoever.

Let go.

Let the mind unite in a single point and let that composed mind dwell with the breath.

Let the breath be its sole object of knowledge.

Concentrate until the mind becomes increasingly subtle, until feelings are insignificant and there is great inner clarity and wakefulness.