I not only say the phrase 20 times in the morning before I get up and at night before I go to sleep but anytime I think of it during the day. It's sure better than some of the anxious thoughts that pop up on their own. As soon as I get one I switch to the affirmation. It's the simple process of thought choice. Replacing a wrong thought with a right thought.
Here's how I get from Beta level to alpha level at night when I go to sleep. I did pick up one helpful Coue hint which was easy to add to my technique because it is to be used at the very beginning. So I now start with staring above my head, as far back as I can until my eyes get heavy. Then I close my eyes, relax the muscles around my eyes, let that relaxation go to the rest of my my body by starting with my toes and going through my feet, my legs etc, saying RELAX, RELAX and relaxing each body part. Then I take a deep breath and count down 500, then 300 then 100. Then I say DEEPER AND DEEPER. I say these things in my mind, not aloud. Then I count down from 10, 9, 8 DEEPER AND DEEPER, 7-6-5, DEEPER AND DEEPER, 4-3-2-1 DEEPER AND DEEPER. Then sometimes I count really fast 1-2-3-4 several times to block any intruding thoughts. Taking deep breaths and then I start to say in a barely audible voice the 20 repeats "Day by day in every way I am getting better and better.
And one small triumph. I noticed the other day that my feet were always sweaty lately. When I took off my socks for any reason they were just wet. This is not usual so I figured it was part of the anxiety. I noticed last night that my feet were no longer sweating.