Atletico won the Copa del Rey last season, while they have also tasted success in Europe over the last couple of years.
"We are working very hard for the team to maintain this level all season, but the road is very long. We want to get as far as possible and we are showing that we have the team for it," Courtois told Sportium.
"It has improved a lot since Simeone arrived. He is one of the best coaches in the world, he's well motivated and gets the best out of everyone. He has instilled his winning mentality."
Courtois is currently on loan at Atletico from Chelsea.