Are affirmations helpful?

Are affirmations helpful? do you think affirmations or a change in mindset can end stuttering or somehow reduce it? if yes, what affirmations would you recommend? I have been saying in my head "I speak fluently" for a few months now and I notice that sometimes saying this instead of thinking that we will definitely stutter on a word really helps, of course it doesn't always work but it’s working sometimes. I would be very grateful for your help. and apologies for my english.