Park has admitted that he was disappointed by the non-selection but said it only inspired him to remain at Old Trafford and work harder for success.
"That night was a big disappointment for me," he said. "I didn't want to leave because I felt I could do more to make it at United. That is why I stayed.
"I felt it would eventually happen and I believed we would reach another Champions League final, I just didn't expect it to be the following year."
And Park added that he now feels a lot more comfortable and confident when wearing a Red Devils shirt compared to when he arrived from PSV Eindhoven in 2005.
"I feel better about being at Manchester United, " he added. "When I first came I was a little bit worried that I would not be a success. But that always happens.
"You never know you are going to succeed until you have. What I was going to do at the time was more important. I just tried to do my best and once I started training I totally forgot about my concerns.
"Now I feel quite confident. Mentally I am in a good place. The fans have also been supporting me. It makes me more assured about showing my ability on the pitch."