What are the four major components of physical fitness

Aerobic Fitness.

Aerobic fitness improves overall health and well-being.

Muscular Fitness.

Strength training improves your muscle and bone health, and helps with weight loss.

Flexibility.

Flexibility allows you to move your body freely.

Stability and Balance.

For balance obviously.

If it's a smaller child or infant, place one on the middle of the chest and on the child's back. (if it is a bigger child with enough room for two, place one on the upper right/your left of the chest, and one on the lower left/your right) the pads should never touch each other.