Sisu

Sisu is a 500-year-old Finnish concept about finding inner strength when things feel really hard or almost impossible.

It helps you keep going and is all about resilience, courage, and grit in tough moments.

The word originates from sisus, which means “inside,” and it’s a big part of the Finnish mindset.

Sisu became known worldwide during the Winter War (1939–1940), when Finland held off the Soviet army.

Historically, it implied stubbornness, but today it’s seen as a positive, action-oriented form of willpower, helping people survive extreme challenges.

Researchers Emilia Elisabet Lahti helped define its modern meaning.

Unlike normal grit, Sisu isn’t about long-term effort; it appears in intense moments, when you feel like you’ve hit your limit but keep going anyway.