The Republic of Ireland winger accepts that it was a tough period in his career on and off the pitch last term as he struggled to find his best form and became embroiled in a Twitter row.
Having been warned about his use of social media, McClean is now focused on the future and is keen to impress new manager Paolo Di Canio when he reports for pre-season duty.
He told Sky Sports News: "It has been difficult for a lot of reasons, which have been well-publicised, but that is all in the past and I will go back soon for the new season and hopefully push on.
"Each manager has a different style, so hopefully next season I can push on."
McClean concedes that his future at Sunderland is unclear but he is staying relaxed and hopes to show his best form.
He said: "Whatever happens over the summer, happens. I am just keeping my head down and doing the best for me personally and whatever comes of that, comes of that."
McClean is currently on international duty preparing for a home game against Faroe Islands on Friday, and he has set his sights on an important victory for Republic of Ireland.
He said: "It is not going to be as easy a game as people think but I will be looking for us to get three points and hopefully we can do that on Friday."