The young striker said the chance to move to the Santiago Bernabéu was impossible to turn down, while describing the manager's close attention and demanding approach as important to his development.
Espí joined Real Madrid from Levante during the summer and has experienced a rapid rise, earning a second call-up to Spain's Under-21 squad. The forward admitted that the speed of his progress had surprised both him and his family, but said he was determined to keep working and make the most of every opportunity.
"It's incredible everything that has happened to me. Nobody really expected it, including my whole family. Now I have to keep working. It is difficult to take everything in because it is all happening so quickly. You have to be ready because it never stops," he told Cadena SER's El Larguero.
The 19-year-old confirmed that he had attracted interest from English clubs before committing to Real Madrid. However, the opportunity to join one of the biggest clubs in the world quickly settled the decision.
"There were options to go to the Premier League, but when Real Madrid come along, I couldn't turn it down. Everything happened very quickly; the whole thing was closed in two days," he said.
Espí is aware that competition for places at Madrid is intense, but believes the experience of working under Mourinho is already helping him improve. He particularly values the manager's willingness to communicate directly with him, identifying both the positive aspects of his game and the areas that require further work.
"What stands out about Mourinho is how incredible he is, how approachable he is and how demanding he is. The fact that he pays so much attention to me is very good. For him to tell me what is good and what is bad is very important for me," Espí said.
The striker also revealed the advice he receives when discussing his limited opportunities in the first team. Mourinho has encouraged him to remain patient, continue working and be prepared to take advantage of any minutes he is given.
"Mourinho tells me that I have to be patient. I have to make the most of every minute and every opportunity. That comes from working every day. Every minute he gives me is worth its weight in gold," he explained.
Espí's attitude is to concentrate on his development rather than become frustrated by the competition for places. He believes his move to Madrid is an opportunity to learn from elite players and improve under a coach with extensive experience.
"I have come to Real Madrid to learn, improve and continue growing. I am going to fight for Real Madrid and I am going for everything," he said.
The forward also spoke about the opportunity to train alongside Kylian Mbappé, whom he considers the best player in the world. Espí said he tries to learn from the Frenchman's work in training and values the chance to observe him at close quarters.
"Kylian is incredible. Every training session, I try to learn from what he does and what he tells me. He is the best in the world. For me, he deserved the Ballon d'Or," he said.
He added that Mbappé's speed, ability in one-on-one situations and dribbling particularly impressed him, describing it as a privilege to share the training ground with the forward.
For now, Espí's focus remains on earning more opportunities at Madrid. His Premier League options may have offered an alternative route, but he is convinced that choosing the Spanish club was the right decision.