Unfortunately doesn't work for me and I was positive going into this. Least I know it's not a psychological limit holding back my performance. That may be as I already use my imagination to put myself in the zone when lifting.
When counting up reps I like to see myself climbing a mountain. It becomes easier for me the closer I get to the top, looking back down at how far I've already come, it wills me on and that perspective makes the summit look far less imposing. The first few reps are usually the toughest while the last are easiest (psychologically)
I have a training partner who is quite inconsistent. Mood tends to dictate his performance in the gym so I'm willing to bet this may work for him.