We often want to hold onto happy and joyful times, as long as we possibly can, and when they pass, we hold onto the memory. We want to hold onto those we love, as we know the sorrow, pain and suffering, when someone we love dies. As time passes, memories seem to fade and we experience that pain of loss again - and again - often finding it oddly comforting to choose to spend time with those memories.
We don't want them to fade, we don't want to lose them - often finding it a struggle to remember the loved one we lost - how they looked, how the sounded, and even their scent. We can find ourselves clinging to such memories, desperately longing to see our loved one again - one more time, one more hug, one more kiss - and it is easy to get stuck in our memories.
The same can be said for difficult and painful memories and experiences - we can also find ourselves clinging to those, trying to understand "why" - why did this have to happen, why would someone treat me that way, why did I choose to behave that way, and so on. Buddhist philosophy and practice suggests that all human suffering is the result of this "clinging", as it keeps us locked up in the past and worried about the future - which keeps the present moment out of sight. In order to experience the present moment, we have to let go of the powerful desire to hold on. Free of the past's pain and free of the worries about what is to come, we can be mindful of every moment, every experience in the present, enjoying our relationships with ourselves and those we love - without "clinging" to them. When we can experience this "letting go" - as fleeting as it is - we achieve true "balance", which is always a work in progress.