I think it's fantastic that you're consciously dieting to be healthier, and NOT out of problematic body image or stuff like that.

Do you weight train? I ask, because one way that larger people can be fat and fit is to make sure that their muscles are strong and supple. That way, you use your muscles to hold up your posture, and don't put as much strain on joints (knees and hips). Plus, it's a way of exercising that is less likely to lead to injury (if done carefully), compared to aerobics, jogging, etc.