As a Finn I see wikipedia article very well written and balanced even though authors are not born in Finland. Just few remarks: -To really understand why Sisu is in Finns heritage and DNA you should study longer perspective (hundreds of years), the conditions like 1)climate, what it takes to settle into country totally covered big trees and soil full of broken stones after Ice Age broke the mountains and and very short growing season, bears, wolves etc. 2)events in the long history with Wikings, Swedes, Russians. -More recently Winter War (linked in wiki article) demonstrated in population level what can happend when whole nation has had enough, unites and hits into 'Sisu mode' where nothing can come in your way. -As article and references points out Sisu, even trationally found amongst Finns, is a quality of many populations. I can recognize reminders of it in old stories of first white people settling to North America, exploring wagon routes to west or exploring Klondike. Even more recent climpses can be seen in todays light reality series like 'extreme makeover', 'undercover boss' where good hearted people are working 2-3 jobs just to provide their family and kids.

Should we all then try to reach 'Sisu mode', my answer is no or only when really needed. As in that Wiki article famous Finnish rock singer compares Sisu and adrenaline, I partly agree with him. Adrenaline is not Sisu, but probably when you are in 'Sisu mode' adrenaline is pumping full. That means extra cortisol in your body (also stomach), which is not healthy in longer doses as we know.