Sometimes we all just have a day when things just aren't working in synch. If you can focus a bit on what is going wrong, then it's a great opportunity to grow as a shooter. My personal issues on these days is generally a lack of focus. If its a physical thing, such as grip, trigger control, etc., it's pretty easy to pay a bit of attention to that and get back on track.
For me, the lack of mental focus is harder to deal with. Shooting really is about 90% mental so it's easy to loose focus sometimes. On those days, I just try to make it a fun day and not waste ammo or work on a single factor I'm having issues with or want to improve on.
Shooting at a decent level contains a decent amount of auto pilot where a number of things work best without a lot of conscious thought. Too much mind can screw with that.