In plainest terms, flex all of your body's muscles to the best of your ability during your tension points and let out a deep breath from your diaphragm. However, when you can do this kata and its tension sufficiently for any of your belt requiremnts, i encourage to stop practicing with the tension. This is because the type of tension used in Sanchin is what is known as an isometric contraction, and isometric contractions of this type squezze your blood vessels when the muscles flex and in turn, raise your blood pressure if continually practiced. In short, flex your body, when you get good at it, stop doing it.
Agreed. Read the "sanchin tension" thread. After this became more in depth discussions, I found out that although what i said is true temporarily and isometric contractions can cause temporary blood pressure increases, they can actually have a positive effect long term. I'm sorry for previously misinforming you due to my ignorance.
OK people, I am locking this thread as there is currently another thread on the subject here: http://www.martialartsplanet.com/forums/showthread.php?t=15729