"It was beneficial for me to arrive at Arsenal last January so I had six months to get used to the league, the country, the culture so I could be ready for my first full season," he told ESPN.
"It was not easy at the beginning six months ago. It was such a big change. It was hard to find the rhythm, especially physically.
"But this time, I am ready.
"I am really feeling good."
He added: "Personally, I want to contribute as much as possible with goals and assists.
"I don't have a figure in mind but I really [think] it will be a very good season like the ones I had in the past at Dortmund."