The 27-year-old made the switch to Stadio San Paolo in a reported €10million deal in the close-season, after failing to become a regular starter at the Bernabeu.
Callejon has responded with a return of 12 goals in 32 Serie A appearances for Rafael Benitez's men, in what has been an impressive debut campaign.
The former Espanyol man concedes he found it difficult to depart a club of Real's stature, but stated a desire for first-team football made it a necessity to leave.
He told Corriere dello Sport: "I left Real Madrid in order to find greater consistency to my performance, in order to play more and to make a change in my career
"It has not been easy, (Real) is a club it is hard to leave, but at some point my love for football prevailed and I went to Napoli.
"Benitez described the project and spoke of this club. I had some offers, but I was convinced by everything. Now I can confirm that I was not wrong.
"In Madrid, football is important, you live with this enormous pressure. But here it has the same worth as religion.
"I feel good here and I feel the support of the people. I hope to go as far as possible with Napoli."
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