The midfielder is in the final stages of the show in Italy, making the top 10 from thousands of entrants.
Liverpool and England star Jamie Redknapp, who hosts the series, took Craig aside in one recent episode to talk to him about being homesick.
Redknapp encouraged the up-and-coming player to make the most of his opportunity.
Craig admitted it was "hard dealing with the heat and the homesickness" in Italy, but he got over it and believes the experience has made him a stronger.
He described Redknapp as "an amazing person" who helped him off camera as well as on. "He was so helpful," Craig said.
Redknapp even described the young Dubliner as the "complete footballer" because of his range of passing.
Craig said it was an "amazing" compliment, especially "coming from the mouth of someone who has done it all".
The teen has already played for the Republic of Ireland at U-17 level, taking part in the first international to be held in Tallaght Stadium in April.
Craig said it was a "dream come true" for him.
Open to footballers aged 16 to 18, Football's Next Star offers the winner a season's contract with the reigning Italian champions.
Redknapp was joined by a team of Inter's top coaches and scouts for a series of open trials in cities across Britain and Ireland, where thousands of young footballers tried out.
The best 40 players had further tests in London, before 10 young footballers were selected to travel to Italy to spend five weeks at Inter's state-of-the-art training complex, Interello.
The finalists worked with some of club's biggest stars, including Javier Zanetti, Samuel Eto'o and Marco Materazzi.
Living in a luxury villa, the participants received a unique insight into Italian football and culture.
Redknapp mentors the players, and Milan's team of coaches will be joined by Mourinho in making the ultimate decision and selecting the winner.
Due to his contractual obligations, Craig could not reveal how far he went in the show.