Ideokinesis and the exercises on our site are a "non-doing." By "non-doing" we mean that the ideokinetic exercises require you to image things in your mind, but not directly act on them with your body.
Over days, weeks and months, as you practice these images in your mind, you will reprogram your habitual posture and feel, in a new way, your body, its alignment and your movement.
The best way to do these exercises is to relax and try them for a few minutes each day. You can quickly work to a point where, when you get up to walk, you say to yourself: "Imagine a tail," or "Down the back, up the front," etc.
Another suggestion is not to dwell on these images. Life is too short and you have too many things on your mind, anyway.
As Irene Dowd writes in her Taking Root to Fly, "all postural alignment patterns, all muscle use and development, all human body movement is directed and coordinated by the activity of our nervous system, in other words, our thinking. Therefore, in order to change our body shape or our movement patterns we must change our neurological activity....to change the habitual patterns of messages being sent from the brain through the nerve pathways to the muscles."