Bayern ended the season empty-handed with defeat to Bundesliga winners Borussia Dortmund in the German Cup final before the bitter disappointment of losing to Chelsea on penalties in the Champions League final in Munich.
However, two weeks on from that particular low, Muller is keen to get back into the winning groove with Germany against Portugal on Saturday evening.
"Of course the season with Bayern is now behind us," he said. "It looked like it was going to be such a good season, but then losing those two finals in two weeks, and the way we lost them, doesn't really make you very happy now, does it?
"Speaking for myself, it no longer weighs me down. Things move so quickly in football and that was already two weeks ago and now we are focusing on the European Championships.
"When I am with the national team, I only think about the national team. Maybe in five years' time I will be sad again when I think about it (the Champions League defeat), but now I am excited to be here."
The disappointment of Muller and his Bayern team-mates, combined with their late arrival to the Germany squad, has hardly made for the best tournament preparations, but Germany coach Joachim Low is confident his team is settled and ready after a week of hard work together.
"I am delighted it is now getting under way," he said in Lviv. "We have a good feeling and we are looking forward to this game against Portugal. Now is the time to get going."
Cristiano Ronaldo was equally keen to get onto the field tonight as he cut a relaxed figure alongside Portugal coach Paulo Bento at the pre-match press conference yesterday.
"At the moment, I don't feel any anxiety," he said. "The whole team feels good. Maybe the adrenaline will get a bit higher come the game, but right now I am not nervous at all.
"The team is in a very good condition and we are well prepared."
That is just the way the Real Madrid forward would like to feel come the final whistle tonight too as he lauded the atmosphere in the Portugal camp.
"You have got to enjoy yourself, that is important in any side," he said. "We have a very good team spirit and that is why I am very confident.
"We want to work for each other and show ourselves off. This is our strength."