Lingard was handed an extended holiday after the World Cup in Russia.
But just days before Manchester United’s Premier League opener against Leicester, the midfielder has returned to Carrington to begin his pre-season.
The 25-year-old posted a video to his Instagram story on Sunday after undergoing a workout in the sunshine at United’s Carrington training ground.
Walking across the pitches at Carrington, Lingard said: “Easy, easy, easy, easy, easy work.
“Paulo (United coach) didn’t want to run did he today? Me on my own running again.”
During his time away from United, Lingard had been working on his fitness with Old Trafford team-mate Marcus Rashford.
The pair met up in Miami last weekend and posted clips to Instagram of their gruelling beach workout in the Florida heat.
While Lingard is only just returning for pre-season, Rashford headed back to training last week following a plea from manager Jose Mourinho.
The Portuguese boss called upon some of his players still on summer break to cut short their holidays and return to training early following a difficult pre-season with a depleated squad.
But Lingard’s return will be a huge boost for manager Mourinho following their defeat to Bayern Munich last night.
The Red Devils ended their pre-season campaign with a 1-0 loss to the Bundesliga champions and Mourinho admits his side will have a difficult season unless they add to the squad before Thursday’s transfer deadline.
“My CEO knows what I want and I still have a few days to wait and see what happens,” Mourinho said on MUTV.
“The other clubs who compete with us are really strong and already have fantastic teams. Or they are investing massively like Liverpool, who are buying everything and everybody.
“If we don’t make our team better it will be a difficult season for us.”