APPLYING ACCEPTANCE AND COMMITMENT STRATEGIES
Recognize and say, aloud if possible: "This is a "mood". It will pass."
Of course, on any negative thinking, you never, never, never allow yourself to entertain the unwelcome toxic guest.
Never, never, never go without a rational response. And practice, practice, practice, so you'll get better at it and quicker. (As I did get quicker, the moods seemed to not have happened at all; they just seemed to pass so quickly.)
Always do, preferably in writing but some effectiveness in oral:
1. Describe situation
2. Describe self-critical thoughts - Before each thought, instead of just saying it. say "I am having the thought that...", so that it is clearly labelled. And then say "I notice I'm having this thought." (This called cognitive diffusion, as you label and identify things more appropriately.)
A. Always say this is a "made up", a mere thought
B. Ask "Is it true?"
3. What are the consequences of this thought (not the situation): Describe feelings and behaviors of yours.
4. Give a rational response (or other argument). (Bring in your rational other; yourself or
someone you know as being rational and caring, both.)
A. Could this be true or as true as the other?
B. What is the evidence on the other side (say something even if you don't feel like it!)
5. Write out an affirmation to use for this.
You are like a bus driver with a number of unwelcome passengers who just don't seem to go away (but they have no physical impact in that they can't strike you). You can choose to accept them and just enjoy the ride.
AM I PERMANENTLY THIS WAY?
"I always screw up, give up, don't finish things..."
First of all, that will not pass the Truth Test, for you must have done some things right and the preponderence of what you do seems to work out, though you do "screw up" because of lack of knowledge.
Therefore, then, the solution is obvious: Increase your knowledge in the critical areas. "But I'll never do it."
First of all, without arguing about that specific, answer "is it possible that some person could, or has, succeeded in doing that?" "As a human being, am I capable of learning, whether I use that capability or not?"
So, it is doable, right? It is just that you think you won't do it because of your past performance.
But it is absolutely true that you are not permanently that way. That would be a preposterous, ridiculous thing to believe.
BUT IT MUST BE TRUE, AS I HAVE LOTS OF EVIDENCE
THE EVIDENCE ON THE OTHER SIDE
Does it really matter if I am not as good as someone else, in a particular area or in all of life? Sure, we might like to be better, but where we are might already be pretty good.
Understand that this involves the key viewpoint that underlies unhappiness: See that you are missing something versus seeing what you have (and then there is the question "is that enough?"). Read about it....
A STORY FOR EVIDENCE ON THE OTHER SIDE
I CAN PRACTICE WHAT THE OPPOSITE KIND OF PERSON DOES
The loser traits versus the traits of the confidence person. Note that it is the traits, which are changeable, that determine the nonpermanent way of being, but that as you practice the good stuff it becomes more and more habitual (doing and thinking-wise) that it becomes a regular state of being. Read Contrasting The Confident Person With the Less Confident Person which is a form in the piece The Completely Confident Person.
Consider Acceptance And Commitment Therapy (ACT). It has solid evidence of workability behind it. It encourages clients to detect their thoughts, and to see them as hypotheses rather than objective facts about the world.