Good rest and nutrition is also very important, from a physiological point of view. I agree practice makes perfect (and legal) but these guys already said that all, so here goes:
Recent evidence shows that having a high mean creatine protein level increases mental endurance when the body is put under stress. To have a higher mean creatine level it's important to have a high meat based protein intake. I suggest poultry as red meat can be extremely unhealthy in large amounts. If you're a vegetarian then you can use protein powder supplements, but be aware that they can make you gain weight, especially if you don't exercise much.
Self-talk or mentally rehearsing actions before doing them has also been shown to steepen an individual's learning curb and sometimes even improve performance. Imagining an action activates the same areas in the brain as performing that action.
Finally, did you know that a high peripheral fat content in a person has been shown to correlate with fatigue? This is only a correlation though so it is still just a hypothesis.
hope this helps everyone!
sources : Effects of creatine on mental fatigue and cerebral hemoglobin
oxygenation, Neuroscience Research 42 (2002) 279/285, Watanabe et al.
http://jtoomim.org/brain-training/wa...talfatigue.pdf
The effects of the reciprocal and the self-check styles on pupils’ performance in primary physical education, European Physical Education Review 2011, 17(??), 35 - 50, Athanasios Kolovelonis et al.