posted by Nene .
It’s hard to believe that a woman her age could accomplish so much.
my reply is I believe this sentence is correct so no change
It'd be better to leave out the "woman" and "her age" elements. How about this? ~~> It's hard to believe that a person could accomplish so much.
AS Writeteacher says, the sentence isn't politically correct. However, your sentence is correct grammatically. :O)