How do I convince my very overweight mother to lose weight and take cars of herself?

First off, I just want to say I am so proud of all of the people in this community. I am glad to have made friends so many of you. I feel since you have all been so helpful for me and to others, maybe you guys can tell me how I can motivate my mom to be healthier .

This may gross some people out :

Today she asked me to treat a rash and some skin problems she is having under a fold of skin under her neck. It breaks my heart to know that my mother is eating herself to her grave and to see her clearly very upset about it. But the problem is she is lazy. She sees me work out all the time and it makes her happy to see me stay fit. So I always invite her to come on a walk with me but she never does. She eats very poorly and drinks coffee like crazy. Complains aabout problems going to the bathroom, headaches and chest pains.

I love her. She is my mother and I feel like I have to help her be a healthier person not by some obligation but because she deserves to be happy with herself and not be in such frequent discomfort or pain... We all deserve that.

So, how do I convince her to change her life?

Thank you.