Mourinho appeared downbeat after a lacklustre performance made a mockery of his pre-match target of United climbing into the top four by the end of the year.
‘What is the solution? I can not change players’ natures dramatically,’ Mourinho said.
‘The solution is that probably I have to make certain choices based on heart and then probably I will blame myself because I will think heart is not enough and I am missing some quality.
‘It is a bad result. We moved Crystal Palace to the sides very well by analysing the opponents but there was not enough intensity, not enough desire.
‘We played as if it was just one more game, not a game we really needed to win.
‘My feeling is it wasn’t enough from the heart. We must play with brain but we must also play with heart and my feeling is there wasn’t enough heart.’
Given Mourinho’s recent state of war against the ‘soft’ modern footballer, he also appeared to question how badly it will hurt some of his squad to have a poor result.
‘Every individual is different. There are people who have a bad dinner, there are people who will enjoy a nice dinner and there will even be people that will party. I am what I am,’ he said, a signal he will remain miserable all weekend.
Palace, who have not scored at Old Trafford in six visits, had 13 shots compared to United’s 12, in front of a watching Sir Alex Ferguson.
Mourinho insisted his work in the build-up to the game was right.
‘We did the most difficult things apart from scoring because we found the spaces to play against a team that marked very tightly,’ he explained
‘I was happy at the beginning of the game because I looked at the game and saw our training sessions, knowing that (Wilf) Zaha doesn’t defend the space in behind him.
‘But we didn’t have the intensity that is basically related to your brain, with your heart.
‘Of course there is frustration but what can you do when there is a match in two days time. There is not a long time to be mourning because on Sunday there is training.’