The 20-year-old left-back reported to Louis van Gaal overweight after signing from Southampton for around £30million last summer so took the steps required to avoid a similar situation this time around.
During United's pre-season tour of the USA, Shaw spoke to the Daily Mail about his decision to appoint a coach for he and Januzaj as they look to force their way into van Gaal's first team in 2015/16.
'"I only had myself to blame last summer," Shaw told the club's official website.
"I didn't arrive at the club in the correct shape and things didn't go to plan. The manager told me his feelings and I totally accepted that.
"At a massive club like United you have to be at your best. But I learned and this season I feel much fitter, much sharper and I have the experience of a year at Manchester United behind me. The big difference is my fitness.
"Adnan and I decided to ask a member of the United coaching staff to come with us to Dubai and we paid his flights.
"He worked us in four sessions per day. We had a football pitch, a gym and an altitude trainer, we did beach runs too."
Shaw added: "The most important thing for me was to come back fitter pre-season.
"I have come back to this pre-season in much better shape than I did last season. The rest has done me really well, the trip to Dubai helped also and I feel good."