Vidic has returned to action after last season was wrecked by a knee injury. It has been a tough road back, with lengthy treatment and rehabilitation.
He said: "It's hard not to play for eight months.
"It's not hard to train and do the gym work because I know the benefits and I have a real desire to do well, whether I'm exercising or playing. It's frustrating when you look at the players training, playing football and being involved in games.
"That's what I missed.
"What drove me on was trying to come back and be the same as I was before the injury or even better, if possible.
"Obviously it was a long time but at first I had to focus on getting the leg right.
"After that I had some physical work to do. But I gave my best to recover as well as I could, so that when I came back I would be fit and competing every week - that was my target."