A simple way to sit straighter

You can practice this effective way to straighten the spine while sitting on the floor, in Sukhasana (cross legged) or in Vajrasana (Knees bent and heels under the hips) or even while sitting in a chair.

Close your eyes, bring your attention to your sit bones and move our taibone in and lengthen your spine up to behind your nose. Visualize your spine in your mind's eye. Direct more and more prana into your spine (by deep breathing) until you are fully lengthened and can sense each vertebra coming alive. Focus precisely on moving upwards every vertebrae and disc in your spine. Keep the sitbones anchored down, just like anchoring the feet in Tadasana (Mountain pose).

Now bring your focus to the head and neck. Feel your head balancing on the top of your spine by lengthening the back of your skull and drawing a line from the upper palate to the back of the skull. Now relax your eyebrows and all the muscles in your face. 

Take a few quiet, conscious breaths and feel the vitality of a correct posture!