The most important lifestyle choice you can make to improve physical fitness is
a. washing your car
b. participating in regular exercise
c. choosing a more active job
d. cooking meals

Common sense tells me B.participating in regular exercise.

Participating in regular exercise is the most important thing you can do to improve physical fitness. Yes, eating right is needed too but if you only eat right and do no physical exercise, you will lose muscle mass. If you lose muscle mass, you are actually not as physical fit as when you started. Therefore, regular exercise will create lean muscle mass and in turn will make you more physically fit. Some of the exercises you may do that are not strenuous are walking and hiking. These get you outdoors and if you hike, you can get a little more out of the exercise and you will burn more calories. You should also add in some light weights and if you do not have weights, you could use soup cans. What makes exercising so good for you is that it raises your heart rate and creates blood flow while working your muscles. Therefore combined with a healthy diet, exercise will elevate you to being physically fit.