Part of the mind keeps a picture of how things were, and measures the present against it — the old role, the old body, the old normal, the way someone used to be. The present keeps losing the comparison.
Change isn't the problem; the resisting is. Holding the old shape against the new reality doesn't bring it back. It just adds a second weight — grief for what was, on top of the work of what is.
You can honour what's gone and still meet what's here. The day in front of you can only be lived as it actually is, not as a worse copy of a better yesterday.