Yep, I learned to do that, also, Makes a huge difference! Took a concentrated effort for me to relax. and, I usually try to talk about something unrelated to the injection. Even something as simple as complimenting the nurse on the color of her uniform that day.

In my old age now, I sometimes talk, and remind myself out loud to relax my shoulder and arm before an injection. Of course, I have to do that when I am using a curb also, to step right foot first, since left leg/foot has no feeling. More than once I have taken a tumble, even with my cane!
Ginger