Dalila, why do you have to work on affirmations? Could your T use some other techniques with you? I think I would have a hard time doing them too, as they would feel very fake, like lies, and contrived, like mouse said. The closest I have come to this is that in EMDR I have to give a positive statement about myself so we can rate how true I feel it is before and after the process. I have a hard time with this. The one I tend to use is "I am strong," because I really do believe that. But it would be deceitful and counterproductive to say things I didn't believe. Authenticity is a strong value in therapy for me and my T.

Like PsyChris said, maybe saying things that are more indirect but yet positive, might satisfy your T. Like one thing I said to my T last session was "It feels really good to be here."