After winning the Bundesliga, DFB-Pokal and UEFA Champions League under Jupp Heynckes last season in an unprecedented treble for a German side, Bayern have continued to enjoy success following Pep Guardiola's appointment as coach.
Guardiola's men are top of their domestic league, lifted the UEFA Super Cup in August and added the FIFA Club World Cup title on Saturday with a 2-0 win over Raja Casablanca.
Bayern will now enjoy a period of rest due to Germany's mid-season break, and Muller believes the team can have no regrets after a superb year.
"It's nearly impossible to play at the level we've done in this calendar year," the Germany international told the club's official website.
"After this win, we can go into a relaxing holiday with a clear conscience."
Reflecting on the Casablanca triumph, Muller added: "Our opponents did what they could to make it a tough match. We would have liked to score another goal or two, but Casablanca didn't make it easy.
"We're happy to be Club World Cup champions. It's a fairytale ending, the well-earned reward for the excellent year we've had."
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