The former Chelsea playmaker revealed he sought advice on how he could improve from Pep Guardiola and Zdenek Zeman after a tough first season at Upton Park.
Zola's job at Vicarage Road is the second of his oaching career, and he has spoke of how difficult it was following his departure from the Hammers.
"It was hard for me personally because I always live the game very intensively, I always take my work home," he told Sky Sports.
"It was tough. That's why I took time off. It was time to go back to basics, to go back to the books and do things that could help me with my managerial career.
"I watched a few teams that I was interested in. The first team was a Serie B team Pescara where Zeman was the manager. I like him and his style of football. I spent time with him and it was very good.
"Then I went to see Barcelona - another pretty good team - and it was very inspirational.
"And it wasn't inspirational because of all the stuff they do on the pitch, it was also the way they conducted themselves, the players and managers. That impressed me very much. Very remarkable."
Zola's Watford face Crystal Palace in the Championship playoff final at Wembley on Monday.