This is wonderful. Before you know it you'll be out of the 300's. Yay!!
I've never done Jazzercise or Zumba, been meaning to though. When I first started out - I walked. And walked. And walked some more. I couldn't go very far at first. So I went more frequently. And I got myself a resistance band.
Anyway, just to back up Lori Bell, not that she needs it, but losing weight and any amount is 100% doable. For anyone and everyone. Yourself included. You've already made a big dent. You keep chipping away and chipping away. Just keep at it. Stick with this.
Tweak it as need be. Keep it fun. Keep it interesting. Be creative. Get into it.
Give yourself this wonderful gift. Before long it will become ingrained in you and seem natural. Hang on tight though, because when those rewards start surfacing, they are over the top PHENOMENAL. And you will wonder why the heck you didn't do it sooner.
I look forward to hearing of your continued success.