Lewis was a reasonably high-profile £15million purchase from Norwich City last summer and despite some positive early showings, failed to live up to some fans’ expectations in his debut year in black and white, ending the campaign on the bench.
But Bruce has been pleased with the condition the Northern Ireland international has returned in, with the defender excelling at the club’s pre-season camp at North Yorkshire’s Queen Ethelburga's Collegiate campus.
“He is a wonderful athlete, the kid,” said Bruce to NUFC TV, when asked about Lewis’ early pre-season performance.
"And it was a big learning curve for him last season. He is only a young boy.”
“We've (also) got one or two back from loans, we will see what develops with them in terms of the season.
“But this is about the players we have got here, all about their fitness levels, which is going to be key.
"The better it is (training camp) the better the player will become.”
In total Lewis made 26 appearances for United last season, which included 20 starts in the Premier League.
Meanwhile, Bruce has been full of praise for the facilities on campus for his players this week, despite having to shelve plans to do their pre-season in warmer climes this summer. United had to cancel a pre-planned trip to Portugal due to Covid quarantine rules.
"The facilities are top drawer and that's why we are probably here,” said Bruce.
“We are only down the road but it is a big week for us fitness-wise and in terms of where they (the players) need to get to. They need to work hard, but it is good to be back.”
Newcastle United take on York City and Harrogate Town in their first pre-season games this Sunday.
Bruce will split the squad, although the manager himself will be at the York Community Stadium Leisure Complex for the clash with the Minstermen, with a senior member of his coaching team taking the side at The EnviroVent Stadium.