Bale is again under the microscope after two defeats to Barcelona in a week.
"Sometimes a player comes into a case of his career, in which he doesn't feel at his best," Modric told the press. "Everything passes though.
"It happened to me in the past. I see him being happy and he has the desire [to do well]. We can't forget what he has done for the club, as these things can be easy to forget.
"He want to work, and he wants to be the same Gareth he has always been. Gareth has a lot to give to the team, and all he has to do is work, work, work."