How would my family go about doing an intervention for my self- destructive MIL?

She doesn’t abuse drugs or alcohol
She’s a heavy smoker
She drinks nothing but coffee and soda
She eats pretty much just junk food
She doesn’t exercise
Dr. has told her that she’ll be dead within a year if she keeps smoking the way she does because she’s getting so little oxygen to her brain
She’s in complete denial and keeps wondering why she’s having so many health issues.
She won’t listen to anyone who tries to tell her it’s because she’s not taking care of herself.

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