... when you're really really stressed? Do you say things like:
Life is unfair
I am a failure/I feel a failure
Things never go right for me
I am a bad person/I feel like a bad person
Good things never last
This always happens to me
Bad things always happen
These beliefs are what you are affirming, they are what feels true for you in your life. When things are going wrong and we ask our self this question, our answers tell us how we really feel about our self, life and others. There is no point in sugar coating something if underneath we feel entirely differently. Affirmations can be either positive or negative, for an affirmation to be true, it has to feel true. Whether or not it is true is another matter, what's important is that it feels true for you. A better question might be, does this belief/affirmation serve me?
You can take one of your statements when you do this exercise and ask yourself what evidence do you have for believing it to be true and then start tapping. EFT short cut diagram and procedure.