The Argentine missed the last two months of 2013 with a hamstring injury, but has scored four times in four matches since returning.
"I'm very happy. I have plenty of desire to come back and play football after such a long time out. I'm lucky because step by step I'm starting to feel better, with a lot of vision to have a great year - not just with Barcelona but also with Argentina," Messi told Perform.
"Every year I start with the same mentality to have a good year. To keep growing and improving, to always be at the same level.
"Before the World Cup we have a lot of important things with Barcelona: we have the Champions League, La Liga and the Copa del Rey and that is not the only motivation for me, but [also] for all of us to keep growing."
Messi recently lost his Ballon d'Or crown to Real Madrid's Cristiano Ronaldo.