"Not being in the Euros gave us all a kick up the backside which maybe we needed," said Chelsea defender Terry.
"We were not playing well and we all admitted that. Now things are going well, we are working hard for each other and the manager deserves a pat on the back.
"He has shown us videos when we did not work back and fight for each other.
"When you see things like that on the screen with the manager standing there, it makes you want to fight harder for your team-mates."
Terry added: "The improvement is there, but we have got to keep it going. There is no point doing it over seven qualifiers and then standing still for a year. The key is to keep steadily improving."