As a musician, I often find myself obsessing over that "difficult" part in a piece, or the rhythm I just can't get right.
When this happens, I unload some of my frustration and spend a bit of time with something simple.
If you're a young snare drummer, get away from all those crazy rudiments and spend 15 minutes just playing a soft closed roll. Or on marimba, maybe the hard piece needs to take a back seat to a half hour of scales. Backing away from the "hard stuff" isn't admitting defeat, it's allowing you time to gain insight and calmness so you can go back and give that tough section another try.
Recently, I was perfecting doumbek split hand technique, using the index and ring finger of the left hand to quickly play alternating notes. This Middle Eastern hand drumming technique can be extremely frustrating, especially when tension creeps into your hands. One evening while teaching, two students cancelled, leaving me an hour to fill. I began with the split hand technique but quickly got "finger-tied" so I stopped and played 15 minutes of simple alternating flams on snare drum, somethnig very similar to the way I perceive the split hand technique, and amazingly, when I went back to doumbek, my hands were relaxed, I had a better concept in my mind of what sound I was trying to create, and...well, let's just say that it was 15 minutes very well spent!