"Winning a title always makes things easier," he told Arsenal's official website. "I could feel a change of mentality in the team after winning the FA Cup. After nine years without winning a trophy, there was heavy pressure on the team and on the club's shoulders.
"That switch of spirit [after winning at Wembley] was shown in the Community Shield - the team played with a more relaxed feeling as our victory in the FA Cup released the pressure.
"We only needed to believe in ourselves. If there was something we were lacking during the nine years, it was self-belief. Once you manage to lift a title, then you feel you can do it again. We all wanted to win titles but for some reason we couldn't. Luckily now we have managed to do it and that changed our mentality."
Arsenal start their Premier League campaign against Crystal Palace on Saturday evening.