MIL makes me crazy

My MIL is a very sweet person with a good heart. I'm grateful for that. But, she drives me INSANE. She decided last night to randomly give me a bunch of advice about how to exercise. Like, she started doing all these weird stretches and squats and told me "you have to do this every time you sit down to talk or watch TV." She then proceeded to tell me that she doesn't have any fat on her body: "It's all muscle." And then she told me that if I do this, I will have no fat on my waist! (I just had a baby not that long ago! Give me a break!) Oh, and she tossed in that they were called exercises for lazy people. She realized I was bothered by something she said, so she explained that she doesn't think I'm lazy. Notice that she did NOT say that she doesn't think I'm fat! Ridiculous woman. She weighs like 100 lbs and eats whenever, whatever, and however much she wants. I'm generally slender but a little curvy, and I've lost more than half of the baby weight already. How dare she try to say I need to exercise every time I sit down to relax? How dare she try to add more guilt to my life when I'm already working from the moment I wake up to the moment I sleep to keep her son and her grandchildren safe, fed, and happy! Now, I just want her to go home. She lives a few states away, and I'm ready for her to go back to her own house and stop with her body shaming, braggy nonsense.