Johnson struck twice in their friendly win over Panathinaikos.
"The gaffer has told me I have to get on the scoresheet a bit more," Johnson told the Pink 'Un. "When you have players like Snoddy (Robert Snodgrass) who can put in quality balls it is up to lads like myself to try and get on the end of them. It will be a long season and I don't expect to play every game.
"He has brought in a few new players and that can help to share the load, but I took a lot of confidence from the fact the manager played me so much.
"When I first came here you could have fielded 11 midfielders so really nothing has changed. It's down to me. I have to work hard on the training pitch and every time I want to show that determination to win and keep the jersey. I know if I take my foot off the gas it can change so quickly."
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