The Dutch fullback is a target for Tottenham this month.
"Of course, I still learn a lot here," he informed MUTV. "I learn to be stronger now than I was when I came here.
"Before, I didn't do gym and fitness but now it's almost every day. I train hard to be stronger and think I'm a stronger person now than I was before. You learn different things in training every day and I think I'm a different player now. I'm a lot stronger.
"If you want to play on the high levels, you have to be strong. I think you need that if you want to be a football player for Manchester United. For me, personally, I train hard and wait every time for my chance to play games. I hope I now start getting more games - the only thing I can do is train hard every day so that is what I do."
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