1. Answering the topic title:

Great answer by @Kriegerd. Shows the huge power of this community and great wisdom of its members.

I will only add a bit: I love EFT and mostly use it to open in negative states. And (not "but") in some cases it helps to find a relieving thought, just one relieving thought from the overall feeling. Many times it's "what if it's not THAT bad?", sometimes it's some other thoughts. Here is a pretty general process that helps me consistently.

It is interesting, how it happens physically: I then feel like standing with my legs steadily standing on the ground, a bit apart (~at the width of my shoulders), and then it helps me to feel into where I am, so that I could find "an outdoor", a way out, a relief from the state I have, I feel it more like an energy, and then I translate it into words.

This has been proving itself to find a stable enough "thought out", a thought that can replace the thoughts that.. kind of digged themselves into me before, as this usually is some physical situation that I see in some one light, and with the relieving thought I manage to replace that overall perception to a lighter one. Then I bask in a relief I got.

It helps to do it on a walk: I stand still when feeling into a state and finding the relieving thought, and then I walk, repeating the newly found thought and basking in its relief. I truly move then into the newly found thought. And sometimes the time comes, when the newly relieved thought is not providing the relief it gave before, but I feel some new space, for a new step forward, a new relief. Then I stand still again, find a new relieving thought, and walk forward with it.

I love how satisfying this process is. And I love how on the point it is: many other processes that help to break the negativity, work more as a distraction, and then later I often come back to the same perception of the situation at hand. The process above helps me to move the very point I'm at, and usually it gives a huge relief, because it replaces the most torturing thought that looked like being impossible to change.

Hope it helps. :)

2. Answering the topic body:

In these cases the thought helps me, "what if it's not the situation that influences what I will experience, but my vibrational efforts I'm doing right now?" Then I pay attention that all the time I'm waiting for the physical outcome, I can still come to one next better feeling thought, and one next, and one next. And I think, "what if this actually matters more than any outcome I will get now?" "What if life put me in this situation exactly so that I do these vibrational steps, improving my overall experience?"

One more thing is then of consideration: to come to a feeling, that no matter what the outcome is, I will be alive and I will be able to be happy, because my happiness comes from the inside.

I know that in some situations it looks like it's impossible to be happy, if the outcome is negative. But then this is exactly the point to work on: that not the physical circumstance will define the way I feel. Sometimes I truly think that this overcoming is worth these unpleasant situations, because it gives such stable standing from inside. As AH say, it's where it truly at, it's where it really works.

And one more thing: I was in many situations, when I did do the tiny possible vibrational steps forward, in spite of the overall feeling of the negative outcome, and exactly the same feeling, that with this vibrational setpoint I'm sure not to get what I want.

But then it turned out good. It now feels like, when I step forward, the Universe steps towards me, and I don't have to go the full way forward in order to get the positive things happening, I just need to go no matter what. Not to give up and continue finding the thoughts that give relief.

By the way, it do not have to be the "positive" thoughts always: in a situation where you feel helpless, the thought "I have the right to hate him", or "I allow myself any emotions" is of huge help as well. Let it do its job, bring its relief, bask in it, then you'll be able to move on to the thoughts that will feel even better.

Good luck :) Metta :)