A desire to affirm what is true or spiritual or more positive, can actually be a form of denial.
What you are actually doing is you are trying to make the bad stuff go away, not by its proper undoing, but by glossing over it, replacing it, trying to create an illusion of peace or happiness, or trying to attack it with images of something you prefer.
Years ago this was my only strategy to deal with long-term unhappiness - to try to pull myself out of the mud temporarily and yearn toward the light and try to be positive and look on the bright side and act as if it wasn't there. And then it pulled me right back into it, because I was being a spiritual ego. I was in denial and using denial to try to make stuff go away rather than dealing with it.
So if you are thinking that you just need to repeat what the Course says, or say your favorite quotes, or use certain magical phrases, in an attempt to "deal with" the problem, what you are doing isn't so much correctional as it is a reaction and a way to try to make the bad stuff go away.
It is not our job to make bad stuff go away. This was an ego strategy and it is the ego's attempt at being spiritual. It will try to cover up bad stuff with a glossy surface layer, painting pretty pictures and having positive thoughts and trying to strive towards a happy-go-lucky attitude, all the while keeping depression and self hatred and thoughts of suicide buried underneath.
Dark shit is not healed this way. It doesn't go away, it merely goes out of awareness. The ego's strategy for dealing with anything has always been to make stuff go out of awareness, in an attempt to create the illusion that it no longer exists. This is how it "got rid of God". This is how it denied sin and covered it up with fake guilt instead of undoing it.
This is how it turns guilt into fear and fear into punishment and punishment into death. It uses a form of denial and replaces it with something which looks, on the surface, to be something initially better or more promising or which creates an illusion of things having improved.
But all this does is KEEP the underlying belief, does not correct anything, and in fact makes things worse, because now you have a solid belief in sin covered over with a nice layer of fake innocence, so now you have two layers of problems.
Don't think that denial only looks like denial. Denial takes on whatever form is necessary in order TO deny the truth, and so it is always deceptive in its appearance. It can look like salvation. It can look like peace and light. It can look like becoming more spiritual or being happier. It is the ego's coping mechanism for trying to "deal with" the underling problem in a way which DOES NOT REALLY WORK, but which SEEMS to work.
So if you are trying to combat the bad stuff with quotes and sayings and phrases as if to say these things is getting your mind to believe them more, you are not really directly tackling the problem. You are not looking at the problem squarely and asking yourself, is this even true? Is it even real? Why am I even believing this in the first place? Just assuming it is true and then using denial to make it go away, does not work. At all. Ever.
We come to the course with the ego, and that means we come to it with the ego fully functional in its efforts to cope with life and to manage what it thinks are problems. Its mechanisms for doing this need to be uprooted. If you have always tried to be light and positive and happy while burying your belief in sin and guilt, then you're going to be in for a surprise when someday that 'body of pain' erupts in your mind and cannot be ignored.
When something happens or someone seems to upset us or something goes wrong, if our response to this is to quote course at it or try to be positive or to "see it a different way" (ie see only the good in it, even though we still believe it's happening), then we are using the ego to do the course and are in denial.
Denying what we've already made real does not undo it and this is not forgiveness. Forgiveness is willing to look directly at the dark shit, with truth and light, and examining what it is made of, where it came from, whether there is any real truth or reality to it, and upon recognizing that it is FALSE, letting it go, rather than hiding it.
If your bath is overflowing and there is water all over the floor and it's starting to leak through the floorboards and go all over the place, the solution is not to fetch a magical mop and bucket or to throw down some towels to soak up the water, or to just shut the door and deal with it later. It's to turn off the fricking tap! The problem must be addressed at its CAUSE, its SOURCE, not in terms of its effects or things further down the line.
This is why we have to QUESTION EVERY ASSUMPTION about the ego or about what's seeming to happen. To question even whether it is even really happening at all. To question whether sin is even POSSIBLE, yet alone whether someone sinned. Accepting anything of the ego as a "given" is a mistake, and all of the reactionary band-aids that you use to try to cope with the "effects" of those "real causes" are not going to work. The only thing that will work is to correct the problem at its source by learning to recognize what it is and what it is not.