Because you can remember. And if you can remember then you are apt to miss things. You are afraid of missing something, because it defies your resolutions to change.
Realize that some things you do now will come to an end because of growing up and/or other reasons. The fact that you’ll miss them calls for more reason to enjoy them, because you never know what will drop out of your life next.
Sometimes to grow means letting go of the things we will definitely miss. Letting go is an act of vulnerability.
And a vulnerability of this kind is identical to strength.