For meditation we must be relaxed yet fully alert and vigilant – otherwise it is impossible to control wandering thoughts.
Just as we need a quiet place to meditate, our posture must be conducive to alertness and vigilance.
First, try lying down – sitting slumped over – and then with your spine straight. You will surely feel that while sitting with your spine straight, you are the most alert and aware.
A straight spine facilitates a free flow of energy up and down the spine and its associated energy channels. This is the posture in which we can sit in a relaxed yet alert state for the longest time without physical discomfort.
To achieve a straight spine with no effort, imagine there is a thread coming from the ceiling, attached to the top of your skull, and you are dangling from this thread: rather than forcing yourself to sit upright, you are simply dangling there.
Be sure our hips, shoulders, back of the neck and facial muscles in particular are relaxed and free of tension.
It is not necessary to sit in the full or even the half lotus pose of traditional yoga, where the legs are crossed with one or both feet tucked up above the opposing knee – as long as the spine is straight, we can meditate most effectively whether sitting on a chair or on a cushion on the floor. Try not to relax against the back of a chair or a wall: dynamic energy flows far better when the spine is straight and supporting itself.
As for lying down, forget it! We can practise relaxation and other useful techniques while lying down, but pure meditation requires all our power of dynamic focus and concentration – which the vast majority of us simply cannot muster while lying down.