The Gills were promoted via the play-offs last season and although their pre-season preparations have been hit by injuries, Fuller is hopeful of another successful campaign.
"A lot of people wrote us off last year but we didn't let that affect us," he said. "We believed in ourselves and we're going to need to again this season.
"We know what we've got to do and if we don't then we'll get knocked over.
"We've got competition for places which is good as it keeps you on your toes. If you're looking over your shoulder it makes you play a lot better as you don't want to lose the shirt.
"The boys have done all the hard work now and we need to concentrate on getting three points as soon as possible. Every team in this league is going to be a big test but we're not going to think negative, we'll take each game as it comes and hopefully get enough points on the board.