How to tell the difference of meaning of "anxiety"

I found out that the word, "anxiety" has two different meaning.
One is feeling of worry. Another is eagerness.
I think the two meanings of "anxiety" are completely different
If someone says, he has anxiety and so on, how can I tell the difference?

In general, context will supply the meaning. 'Anxious' used in the sense of 'eager' or 'desirous' will often be followed by 'to', whereas the 'worry' meaning may be followed by 'about': my father is anxious to know when his car will be repaired, I am anxious about my forthcoming college examination. Although many style or grammar guides frown upon the 'eager' usage, Fowler does not discourage it. The sense has been seen as long ago as 1570. Writers who have used it thus include Jane Austen, Kingsley Amis, Lord Byron, and Flannery O’Connor.

Can 'anxious' be used to mean 'eager'? (Merriam-Webster)