On November 30, 1939, Finland received a violent invitation into World War 2, with Soviet planes suddenly dropping 350 bombs over the nation, and a full-blown raiding army of around 450,000 soldiers, 6,000 tanks, and 4,000 aircrafts entering the Finnish borders. With the Finnish army outnumbered by a huge margin, be it 1 Finnish soldier for 3 Soviet soldiers, or merely 32 tanks and 114 aircrafts, the war was less about victory and more about survival.

As the brutal northern winters went on, with 18-hours of darkness and temperatures dropping to -40 degrees Celsius, the Finns revealed their secret weapon, Sisu. A centuries-old concept in Finland, Sisu denotes extreme mental toughness. Taking action even in the face of extreme odds and impending failure, it was Sisu that kept the Finns going and come out victorious with the Moscow Peace Treaty signed in the March of 1940.

What really happened? Yes, there were around 70,000 casualties on the Finnish end, but this was nothing in comparison to the loss of more than 300,000 soldiers suffered by the Soviets. This made the Soviets withdraw, given how heavy the loss was compared to what was there to gain, and a small word did it all – Sisu.

A Way of Living

While there is no direct translation for Sisu in English, some might be tempted to equate it to Grit. But here is the difference: while Grit is about persevering and passion for your life goals, Sisu is about doing what is needed regardless of the results. Sisu needs no promise of success, but just you and your duty. Cold and clear. In fact, this brings Sisu closer to the Japanese proverb, “Nana korobi, ya oki” (Fall seven times, rise eight).

In Finland, Sisu is considered a way of life. When in doubt, Sisu. What needs to be done, should be done. Single parent balancing two jobs with children and loans, Sisu. Two miles left to the finish line but you already feel dead, Sisu. Everyone seems to be criticizing your new business, Sisu.

Different Battles, One Mindset

You will face the limits of your perceived mental and physical capacities many times in life. But remember, the keyword is “perceived.” If another human can do it, you can as well, and humans have done a lot, from inventing fire and the wheel to landing on the moon and beyond. It is not until we push our perceived boundaries that we know what more we are capable of. And challenges are the calls for you to act, like how only when terrorists forced the girls from attending schools that Malala Yousafzai could stand up against them for the equal right to education.

Joshua Waitzkin, a martial arts competitor and champion chess player, says, “At a high level of competition, success often hinges on who determines the field and tone of battle.” It is your mental toughness — your Sisu — that determines the tone of battle.

Most people let their success and failure define them. They see failure as an indication of who they are. But mentally tough people let their perseverance define them. They see failure as an event. Failure is something that happens to a person, not who a person is. This attitude is what helped carry the Finnish soldiers through the Winter War. Even when surrounded by failure, death, and insurmountable odds, their Sisu did not let the soldiers see themselves as failures.