Oxford University is older than the Aztec Empire.

Several recent(ish) studies have shown that the way you think about stress changes your body’s reaction to it. If you consider stress a useful motivator your body’s response becomes healthier than if you believe stress is harmful.
http://www.ncbi.nlm.nih.gov/pubmed/?term=Accute+stress+enhances+adult+rate+hippocampal+neurogenesis+and+activation+of+newborn+neurons+via+secreted+astrocytic+FGF2
http://www.ncbi.nlm.nih.gov/pubmed/?term=Stress-induced+redistribution+of+immune+cells—from+barracks+to+boulevards+to+battlefields:+a+tale+of+three+hormones—Curt+Richter+Award+winner.
http://www.ncbi.nlm.nih.gov/pubmed/22975465
http://blog.ted.com/could-stress-be-good-for-you-recent-research-that-suggests-it-has-benefits/