United's roller-coaster pre-season ended in defeat on Sunday when Javi Martinez's second-half header earned Bayern Munich a 1-0 victory at the Allianz Arena.
Spain international Martinez nodded in from a corner on 59 minutes as the German champions overcame a lacklustre display from Mourinho's side who face Leicester City at home on Friday.
"In the week, we have to organise the week in a way so we can be fresh for Friday because, on Friday, the Premier League starts. We play for points and it's with the players we have," Mourinho told MUTV.
"There is no time to cry. Players are not going to be here on Friday and we have to go with best possible team and with a great mentality."
Mourinho still remains hopeful of strengthening his side in the transfer window before the August 9 deadline, with Brazil international midfielder Fred the club's top signing this summer.
"My CEO knows what I want for quite a long time," Mourinho told German TV ahead of Sunday's game. "I know he tries to do the best for me, and I still have a few days to wait and see what is going to happen."
Marcus Rashford and Victor Lindelof returned for United on Sunday after their post-World Cup break, although the visitors lost Eric Bailly to injury after the interval following a collision with Serge Gnabry.
"Finally, it's over. Finally, such a difficult pre-season is over. The players were, once more, brilliant, they could not have done better than what they did," added Mourinho to MUTV.
Rashford wore the number 10 short, previously the Old Trafford property of the likes of Wayne Rooney and Zlatan Ibrahimovic.
"He wanted it. He always wanted it," said Mourinho.
"Of course, he respected Rooney and then Zlatan wanted to have it. Of course, he was in the shadow, waiting for the opportunity and now the shirt is empty.
"It's something fantastic for the kid, let's give the shirt to him."
Bayern, under new coach Niko Kovac, will head back to their training camp in Tegernsee ahead of next weekend's German Super Cup against Eintracht Frankfurt.