Witnessing sounds very much like observation. But when I get to observe, sometimes I also get somehow involved, affected. Sometimes, such involvement is so subtle that I get to think I am witnessing, and the only way to understand the lack of being a witness is the tiresome feeling that comes from observing a certain scene for a certain while; which scene, you may ask. Any scene, something that happens on the street, something that someone does, a thought, an emotion, a feeling.
I realized that since witnessing is a state of non-resistance, a state where energy is not wasted, a state where everything gets to be effortless, then no tiredness should come from witnessing. And then an example of witnessing came to me. When we have a certain physical pain there are mainly three ways to go: Indulging, Ignoring and Witnessing.
Indulging would be to focus in the displeasure of the pain causing the pain to reside or even increase. In other words you get to judge the pain as something that you dislike and then you resist it. And what you resist, either persists or grows. This indulging can either be very obvious or very subtle. When it is very obvious we are very aware of hating it. When it is very subtle we may even think we are witnessing such pain, but despite our aim, we still don't like such pain, we still want it to go away. We do not really accept the pain. We simply get to convince ourselves that we accept the pain, in such a way that it gets to flow off of our body. But thankfully the pain and discomfort remain allowing us to discern our not-witnessing.
Ignoring it would be to either search for distractions away from the pain so we forget it; or using pain-killers to get rid of it. In this ignoring state, we get to miss the opportunity of learning from such pain. Imagine that you did not feel pain at all... without it you would never have any indication of things out of balance within your body. If you had a broken finger you would not feel it and therefore you would continue using it, causing even more damage. You would touch boiling water with your finger and would not know that such is burning, killing your finger, until it was to late. You could get appendicites and never know it were there until you actually realize you were dying, if you even get to realize that. Without feeling the inflamed appendix, it never got treatment, and peritonitis got to be the result, which you do not realize either and therefore nothing is done, ultimately ending in death. The idea is that when you ignore pain, you are silencing the alarm, and therefore you are not solving the problem.
The other option is witnessing. This one is the wisest one. In this case you see the pain as it is, you do not take it away or complain about it. First, you acknowledge the pain, it is neither good or bad, it is the alarm: "Ohh, the alarm went off. Where is the alarm coming from? Uhmm, I see. Thank you for the warning". So far I neither like or dislike the pain, it does not necessarily mean that I am going to leave it there or get rid of it. What happens next is that one gets to look deeper: "so what is causing this alarm to turn off?, let's see, ohhh, a broken leg. It means then that I should immobilize such leg and then let it heal. Not keep walking on it, otherwise the leg may die". Fine, now by witnessing the pain I am discerning the steps towards healing, not towards getting rid of the pain. Eventually due to such witnessing I actually get to know what is best, and the pain goes away as it is not needed anymore.
Thus, witnessing is about being in a state of receptivity, not excluding anything but still discerning where the flow goes.