Final answer:
A physical fitness program mainly consists of aerobic exercise for cardiovascular health and strength training for muscles and strength.
Step-by-step explanation:
The two important parts of a physical fitness program are aerobic exercise and strength training. Aerobic exercise, also known as cardio, includes activities that increase your breathing and heart rate such as running, swimming, or cycling. It improves cardiovascular endurance and burns calories. On the other hand, strength training involves exercises that focus on building muscle and increasing strength through activities like lifting weights or bodyweight exercises. Both elements are crucial for overall fitness, as they improve different aspects of physical health, with flexibility and balance exercises also being integral parts of a well-rounded fitness program.