It doesn't seem right that someone wants you to stop doing things that make you happy, and at the same time, increase your quality of life.
Sounds like you got things figured out, good luck with that.
From a instinctive standpoint, it sounds like she feels like she is going to lose you(for whatever reason) because of weight-lifting. Ironically enough, because of the poor way she dealt with her insecurities, she will do exactly that, lose you.
You're surprisingly calm about it.