Many times we are afraid of letting go to welcome changes in our lives. Maybe because what we have "now" is something that gives us comfort and a sensation of safety. It does not mean it has made us happy but it's something we know and it's familiar to us.
If we decide to let go or try something new we're taking a risk into the unknown, and sometimes staying unhappy in the known is even easier then taking the risk to be happy in the unknown.
We should embrace the unknown and the new as they give us the possibly to transform ourselves. As long as we have trust in ourselves we don't have to feel afraid as we are our own lifebuoy in life.
"If you are ready to drop all armor of security and comfort, if you are ready to drop all calculative mind, clever mind, cunning mind, if you are ready to drop the mind itself, all dark parts of your heart will disappear. Your heart will become full of light, desire will disappear -- desire means future. And possessions will not be anymore your clingings -- possessions means the past. When there are no more desires, no more clinging to the possessions, you are free from past and future. To be free from past and future is to be free in the present. That brings truth, God, freedom. That, only that, brings wisdom, buddhahood, awakening."