The young goalkeeper moved to Barca last week from Espanyol after the Blaugrana paid his €25m buyout clause.
Garcia's decision has left Espanyol infuriated, but he insists: "Until the season was over, because we were fighting until the last day to achieve our goal, I wanted to stay focused.
"After that, they were intense days and weeks. I talked a lot about it with myself, my people, my family. I was convinced it was the step I had to take, and I'm happy.
"I was clear it was the step I had to take, but obviously, given where I'm coming from, it's been complicated. I had strange feelings, but I'm very convinced and happy.
"I'm thinking about the first day I put on boots and gloves to train. If we're going to dream, let's hope for years of titles and success. I'm calm and eager to face the challenge."
Asked about facing Espanyol next season, he also told Barca One: "It will be difficult, but also different and special to play there in a different shirt. I'm looking forward to it, and I'll be especially excited."