The Germany international feels there is still room for him to become an even better player on the back of his impressive start to the campaign
The Germany international assisted Pierre-Emerick Aubameyang's opener during the 3-1 Ruhr derby win over Schalke on Saturday.
And having already scored five goals and assisted a further four in 10 Bundesliga games so far this season, the attacker believes there is still room for improvement in his game.
"I want to keep on raising my limit," the 24-year-old told Kicker, adding: "And with this process, I've not yet reached the end."
Reus also feels BVB have become stronger as a whole after they lost the Bundesliga and Champions League to Bayern Munich last season.
"As a team, we've made enormous progress. We have become stronger mentally.
"We know that when we play at our full potential, we win the games.
"If we play at a 100 per cent, which the coach demands from us, we are really tough to beat."
Dortmund, who will meet Stuttgart on November 1, currently trail Bundesliga leaders Bayern by a point.