One of the things she's fated to become is a sedentary weak sister whining about the cruel effort of having to perform any sort of exercise; this pointless torment must, of course, be celebrated by eating muffins and drinking a double-double.
Panel 1: We're at a clothing store or some sort as Annie tells Elly that these jogging suits will really help.
Panel 2: As she looks at herself in the mirror, Elly whines that she feels silly because she's not the athletic type. I believe her; she's more the "stuff her face full of greasburgers and wishtfully moan about how fat she is" type.
Panel 3: Annie answers this object by pointing out that once they hit the street in those, they'll fell like running.
Panel 4: After all, if they simply walk, they'll look like idiots.
Summary: You heard it here, folks: cardiovascular exercise is as crazy as eating sensible portions of healthy foods. This, of course, means that Lynn has no idea how to maintain her figure and will have Elly simper about how she doesn't have the tiiiiiiiiime to exercise and it's too haaaaaaaaaaard and she haaaaaaaaaaaaates it in her weekly letter.