The Dons have lost two of their last three matches, but a successful season to date sees them occupy 11th spot in the table with 17 points from their 11 matches thus far.
Fuller told reporters at a press conference: "We have to show character now. We do not want to get stuck in a rut. No matter how good a team you are it is hard to get out of it when you are losing games. We have to find that consistency again.
"We have difficult away games coming up but when the going gets tough you have to prove that you are up for the challenge. It may not be pretty but we have to roll our sleeves up.
"I have only been at the club for a short space of time but I feel that we can progress. I felt in pre-season we could be pushing for a place in the top half and I still feel exactly the same."
Fuller started his professional career at Charlton Athletic, but did not make a single first-team appearance before moving to Stevenage Borough in 2008.