Hold on for too long or too short

Places' names becoming blurish, pictures becoming yellowish, clothes starting to torn away, things starting to fall apart, people starting to be come strangers..
I tried to hold on to the past when people are saying to let go. I know that by holding on to the past I can't move on, but how if, I still hold some dreams of the past that have yet to come true?
Is it better to let go, or is it better to persevere?