Mammals can generate heat by
hibernation layers of fat perspiration aerobic exercise respiration exercise with their fur to stay warm
A B C D E F G H
Aerobic exercise also contributes to the increased the metabolic rate.
Mammals can generate heat  by Aerobic exercise
Mammals can generate heat by (A) hibernation (B) layers of fat (C) perspiration (D) aerobic exercise (E) respiration (F) exercise (G) with their fur (H) to stay warm