The Black Cats are being put through their paces by Paolo Di Canio, with the standard of training much tougher than in previous years, but midfielder Gardner says it can only be a good thing.
"[The training] is tough, I admit it, but it is a good tough because training is hard," Gardner told reporters.
"I am a firm believer that the attitude to training should be the same as it is in life generally.
"If you work hard in life you get a good life. That is what we are doing as far as training is concerned, so hopefully we will have a good season."