Healthy body/Fit body

Hey all! I have been eyeing the FB low impact plan and bought it while on sale yesterday. :) I was reading the plan and it talks a lot about weight loss. Any advice on how to do this plan while maintaining a healthy weight? I lose weight fairly easily as we eat healthy and are generally pretty active to begin with! I'm 5'4" 128lbs my weight is good, but I'd like to tone and strengthen my body. I want to be healthy and strong physically and mentally.