Coworker is already looking to retire?!? how? iin?

My co-worker is only 39 years old and she keeps telling me how she started working for the company at age 20 and shes like "its been almost 20 yrs. next year itll be 20 yrs i was here. way too long i need to retire"

At first, I thought she was joking but then I asked and she told me that she seriously plans to retire and not work again even part time the rest of her life.

I know her retirement will most likely be around $30-40,000 a yr. How can she get by on that?

She doesn't have a husband or kids, shes alone. I live in the same apartment building with her. I work full time too, same hours.. I pay 1,000 a month in rent and probably over 1,000 in utilities, food, and gas for my car.
-2,000 each month = -24,000 a year. How could she afford that? She tells me shes gonna move into a house too.. houses where we are at cheapest are 200,000...wtf?!