| It happens, still does to me. If I'm finding it hard to focus on my practice I find it'd because my practice is becoming complacent. I'll look to change it somehow by increasing or slowing down tempos on an etude I'm doing, or find a new way of fingering a scale, or sometimes just find one challenging aspect (either a phrase in an etude or peice kicking my butt) and shed that for a while.
Do you practice in an environment that's free of distraction? If not can you make it distraction free? Have you spoken with your teacher about this?
Plus don't be too upset over a few bad lessons, just use the experience to figure out a little something about yourself and use this as an opportunity to grow.
I hope this helps,
Mike | 
