Speaking to the East Anglian Daily Times of the decision, Magilton said: "This was the decision I had to make in the summer because I didn't want to stifle any of the young players.
"I reached an age, when I was with the national team, when I made a conscious decision that I did not want to stand in the way of any of the youngsters there and it was the same again.
"I thought long and hard about it during the summer but the manager convinced me that I still had something to offer. If that means me being here to help these young lads come through, then that is what I will do.
"I didn't want to feel as though they had had enough of me, and the manager convinced me that they have not. This season, probably more than any other, is going to be a transitional period and we need to coach these lads through."
Speaking of fellow midfielder Owen Garvan, tipped by some to take over Jim's role in the future, Magilton added: "I will gladly hand over the mantle to the lad when the time is right – he is a very good player.
"He is going to be quite a player. Once he plays in more competitive matches, and the more he trains with the first team, the better he will become.
"But Owen also knows he is going to have a fight on his hands with me, and that goes for any other midfield player. If they are better than me day after day, week-in, week-out, then they deserve to be in the side."