In just four lines, the speaker admits something a little surprising: watching things grow old makes them afraid of change. We might expect the fear to be of death or decline, but here it is change itself that unsettles them, as if age were a kind of slow, unwelcome movement away from what was steady.
The second stanza turns things around in an odd, interesting way. The speaker says they "used to be old," and compares that old self to a settled business, "content with any little ore." Being old, in this picture, meant being stable and satisfied with small returns, like a miner who stops hunting for riches. Now that calm seems gone.
The mood is quiet, wry, and a bit uneasy. The title, "Golden years," adds irony: the speaker's youth, not old age, sounds like the time of contentment. The poem leaves that puzzle open for the reader to untangle.