Avoid Disappointment!

I have been thinking about the phenomenology of disappointment: how it happens, when it arises, and under what circumstances. Though I have no answer to the question itself, I can say a few things, particularly that I was more easily disappointed when I was younger. My particular disappointments seemed to have arisen from two related things. The first is an unclear sense of what could come out of something: for instance, I might compare what I see on a movie to what happens to people in daily life, only to find the latter wanting in some way. The other source of disappointment seems to be a kind of high expectation placed on the self. I think the latter is by far responsible for the most disappointment, perhaps because disappointment always seems to come back to a very strong sense of purpose that seems frustrated by various things. One example is what happens when meditative practitioners think that they should not experience negative emotions, but then find themselves succumbing to such emotions when they are feeling weak, tired or exhausted. At that time, not only do I feel disappointed in myself for feeling physically tired or 'off', but I then attach that disappointment to a solid sense of self. This is a twofold disappointment.
  Now what happens if, instead of trying to suppress those states of being, I were to simply witness them, resting in the knowing that I am never identical with those feelings? This is what I experimented with today when I was going to the supermarket to buy food after work. There were feelings of tiredness, certainly, but there was also this added sense that I should not feel tired, which then creates an added layer of tension and pressure. If I want to be something I am not feeling at that moment, I create a very big mission for myself. Well--give up on that, because who exactly is having the feelings of tiredness anyway? Asking this question allows me to realize that there is a witness that is aware of the feelings but it not really tied to those feelings. It's like the nature of a window: a window can allow everything to go through it, or to be seen through it, without leaving any trace of those images. Is mind like a window? Indeed, there isn't anything that sticks to it- it witnesses like a movie screen, allowing everything to pass through it but not sticking to anything.
   It's important to really play with this idea and test it out. One day when you are not feeling very well or don't like the feelings you are having, take a moment to reflect: is your mind really immersed in these emotions and unable to emerge from them, or is it only transmitting those emotions temporarily?  If the former were the case, how would mind know that we are 'in emotion'? Think of the analogy: if a window were completely covered with paint, it could not possibly allow other things to be seen through it, yet the window is not covered with paint at all. It simply transmits light in a transparent way, allowing things to be seen as they are before they slip away.