While Messi helped Barcelona to the league title and won his fourth successive FIFA Ballon d'Or last term, the Argentina international struggled with injuries and also had to come to terms with the news that coach Tito Vilanova suffered a cancer relapse.
However, while the 26-year-old admits last season had its ups and downs, Messi is determined to enjoy a better year under Gerardo Martino, who was appointed as Vilanova's successor last week.
"I am approaching the season with great enthusiasm and great optimism. Like I always do," he told Goal after winning the Goal 50 award, which saw 500 journalists vote for the top 50 players in world football.
"It was a complicated season despite winning La Liga."
Messi has fond memories of winning La Liga with 100 points last season with Barcelona, who were dumped out of the UEFA Champions League in the semi-finals by eventual winners Bayern Munich.
"The league is an important prize because it is the result of the work of an entire year, but we had many blows and things which affected us - injuries, other things which minimised our ability to react and, regrettably, Tito's illness," he continued.
"The best moment of the year was, undoubtedly, when we knew that we were champions mathematically. The worst, without doubt, was the relapse suffered by our coach, Tito Vilanova."
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