The Untethered Soul by Michael Singer talks about how we create blocks for ourselves by clinging onto things. To understand what that means lets first let go of who we think we are.
"You are not your thoughts; you are aware of your thoughts. You are not your emotions; you feel your emotions. You are not your body; you look in the mirror and experience this world through its eyes and ears. You are the conscious being who is aware that you are aware of all these inner and outer things."
What does it mean when we cling?
"When consciousness concentrates narrowly enough, it loses its broader sense of self. YOU literally get lost in the experience. This can be generalized to your entire experience of life. Your sense of self is determined by where you are focusing your consciousness."
You then use these experiences that you are focusing your consciousness on to create your entire sense of self around it. This creates a false sense of security in believing that things are supposed to happen a certain way. But lets get real. How often do things turn out the way we thought they would? How limiting is the notion in believing that things only can happen the way I think they will?
Clinging creates mental blocks and pulls our focus out of the present and into a preconceived view of how we think things should be based off a past experience. Whether the experience is good or bad simply take it as that; a life experience. Allow it to be your teacher, learn from it, and MOVE ON. This is how we continue to grow in life and stay open to new experiences. Only by doing this are we genuinely living in the present.