Anyone ever change their work-out time significantly and have trouble with the same level of intensity they were accustomed to having?

I am working out with a different partner, and he doesn't get to the gym until 8pm. I was working out around 4:30 or 5 previously and now have a hell of a time getting motivated and hyped for a good workout.

Sometimes I get done with a set and ask myself why I just did half the reps I normally do!

Any thoughts for jump-starting me back into the proper mind-set or whatever it is I need to get back to where I was in earlier in the day work-outs?