Core strength is important and starting out either when your babe is young and light or starting slowly if they are older and your body isn't used to it. You also have to switch to a back carry before they get to heavy, the extra weight on your front will throw your back out. I am also super careful with how I bend or move, I try to make sure I'm bending with my legs in a squat or lung position and keeping my back straight - the added benefit is super toned thighs from all the squats!