How do you deal with elder bird anxiety?

My buddy is getting up there in years. She's been pretty healthy, but she'd definitely starting to slow down a bit. I get panicked sometimes, thinking about the part of my future she won't be in. I've had her since I was a teenager and I love her dearly. Now, whenever she falls asleep in my hand, I look at her and feel anxiety instead of peace.

How do you deal with anxiety about your aging pets?