This could be absolutely HORRIBLE advice, as I'm no certified trainer but when I was having some issues with my left arm failing before my right arm I would do this:
Truthfully, if I'm having a weak day I'll generally make my last set of an exercise a drop set. Say i'm not really feeling my t-bar row one day, I'll attempt to power through what weight I can for my...
Oh God, i'm guilty of the phone thing. Girlfriend calls me while I'm at the Gym, and I ALWAYS expect it to be a super easy "Hey sorry babe, i'm at the gym right now, okay love you bye"