Isn’t this brilliant. How can we be afraid of that which we don’t know? What we are really afraid of is the thing we know, might not continue and instead launch into the unknown. But it’s the ending we worry for. There is a Zen phrase, ‘half of happiness is being okay with not getting what you want. The other half is being okay with losing what you have’.
Truly, spend some time with this phrase, pull it apart, allow it to reflect on various parts of your life right now, and then reconcile gradually what you can.