I routinely cut my workouts short because of fatigue in the gym. But the weird thing is that I am in relatively good shape. I stick to three compound heavy movements (hang clean & front squat, deadlift and snatch) that make up the bulk of my work in the gym. On non-gym days I will go on 30-45 minute runs of moderate to heavy intensity. Every six days I will take a day off to rest.
I am 21 years old with a solid diet and no alcohol or tobacco vices. I usually only get 6-8 quality sets before I feel like I'm done for the day. Is there something I could be missing?