"You have to learn from your mistakes - but there is a limit to how much you have to beat yourself up. You have to be in your best mental and physical shape."
"It really applies in anything you do, if you set a clear target and focus all of the energy you have. It's just this thing we Finns always have in common. We will find a way and no one will stop us."
The concept of Sisu is an important part of Finnish culture. But why is that?
"I think nature has definitely made our country what it is, made the people what they are, and made the mentality that's the Sisu in us, because it can be quite tough," Valtteri admits.
"Winters are cold, nights are long... but then of course summer is the opposite. It's beautiful. I think just the way the country is has made us who we are."
Through the tough moments, he's always looking for the positives, constantly pushing to learn and get the most out of each opportunity. That's what Sisu is all about.