Sykes lost out on winning the title last year by six points, in the final race in Qatar.
In a chat with Crash.net, Sykes said that losing last year's title the way he did has been frustrating.
"It's difficult. I've lost the championship two years out of three and I put it down to other riders' miscalculations that have really cost us," he said.
"As a rider when it's not your fault it's very difficult to accept because it's almost like your goal is within reaching distance and then somebody takes it away from you.
"Now maybe that's just my perception but I'm very bitter with things like this. All I need to do is work and try and get the world championship back. It's something I dedicate my life to and, like I said, when it's taken away from you by somebody else it's impossible to accept," he added.
Looking ahead of the season opener in Phillip Island on February 22, Sykes believes his Kawasaki team have reason to be optimistic after two promising pre-season tests at Jerez.
"The off season has gone very good," he said. "We had a test which was almost a waste of time just because of the weather but apart from that Jerez was good, consistent weather.
"We had a very productive two-day test and came very close to an acceptable base setting for the Ninja," Sykes told Crash.net.
"I am very happy now. We're going to Australia to fine tune our package and try and get the season off to a good start," he added.