The 24-year-old enjoyed a strong rookie campaign after being drafted first overall in the 2011 draft but struggled in the last campaign, throwing just 19 touchdowns, as his side finished 7-9.
"It's no more excuses on my part," Newton told NFL.com. "First year is gone, second year is gone.
"Now, I'm considered somewhat of a veteran to these guys, you know, so taking accountability on this offense and on this team is big for me, and that's what I wanted to come back and [have as] one of my staples to get better."
Ron Rivera's team open their pre-season campaign next week against the Chicago Bears.