This video on why Russians are better wrestlers than Americans I found quite profound. In general Russians are known as being tough--think Siberia, the battle of Stalingrad--but in wrestling it's the Americans who are tougher, they work harder and are better conditioned. Yet Russians generally dominate American wrestlers.
Ken Primola argues that the Russians are better because they are more cerebral, they are more into technique. As I'm a coach for little kids, I see a lot of the high school and college kids, and know that in America they are taught that the primary attribute of a great wrestler is hard work. Your average great high school wrestler after a big loss will say 'I have to work harder', not realizing it's a cliche. Clearly, to be really good you have to work hard, and to be great, you need some natural athletic ability (see Jon Jones or Anderson Silva in MMA). But after a certain point, everyone has put in 10,000 hours, and so simply working harder has very little marginal benefit.
I agree that any excellence involves a good amount of disciplined effort, yet that only gets one so far. To really improve once at that level you need a better strategy, and that takes better higher-order priorities. Avoid the temptation to work so hard that there is no time left for serious thinking, in wrestling or anything else.