I’m not anti-running at all, I say, do what you love. I’m going to settle the long standing argument regarding calories burned when running vs. walking. Check this out.

Question:

Please settle a discussion between an acquaintance and me.  I walk 9.2
miles frequently for exercise – I do this in about two and a half
hours.  I contend that this is roughly equivalent to running the same
distance as far as calories expended and exercise benefit – it just 
takes longer than running the same distance.  He disagrees and says

that there would be more exercise benefit to running a mile than walking a mile in such
aspects as better endurance, toning, cardio-vascular benefit, etc.  I say the two are 
equivalent and that walking is better on the joints anyway. What is your expert answer
and how can I determine the calories I expend on my 9.2 miles walks?

Answer:

Here’s the answer from Dr. Dean Ornish, a clinical professor of medicine at UC San Francisco:

“All things being equal, you will burn more calories by running an
hour than walking an hour. It is true that walking a mile will burn
more calories than running a mile — although it takes longer to do 
so. When you run a mile, you’re burning mostly sugar, or carbohydrates,
which is how your body gives you fast energy in bursts. When you walk a mile,
it gives your metabolism time to switch from burning carbohydrates to burning fat.”

WebMD – Dean Ornish, MD Q A: http://my.webmd.com/content/article/3079.883

How many calories you burn depends on a variety of factors such as
fitness level, metabolism, weight and the intensity of the workout.
“Larger people burn more calories than smaller people,particularly
with activities like walking or stair climbing where they have to carry
their own weight,” says Robert McMurray, professor of exercise and
sports science at the University of North Carolina at Chapel Hill.

iVillage – “How Many Calories Are You Using — and Other Burning Questions”
by Carol Krucoff:

http://www.ivillagehealth.com/interests/healthy/articles/0,11299,165839_125472-1,00.html

As far as how intensity affects a workout, according to an example
from the The President’s Council on Physical Fitness and Sports, if
you were walking briskly for one mile and your friend was jogging,
you’d burn about the same number of calories if you walked for 15
minutes and he jogged for eight and a half minutes.

The President’s Council on Physical Fitness and Sports – “Walking for
Exercise and Pleasure”:

http://www.pueblo.gsa.gov/cic_text/health/walking/walking.htm

As far as a being better on the joints, walking is, without a doubt,
the better exercise. It’s one of the safest exercises you can do and
it provides great cardiovascular benefits without all of the stress
that running puts on the body.

Yahoo! Health – “Walking Workouts” by Carol Krucoff:

http://health.yahoo.com/health/nutrition_fitness/fitness_tip.html

According to Dr. Ann Gerhardt, a Sacramento, CA doctor who was forced
to walk for exercise after tearing her anterior cruciate ligament
while skiing.

“The other plus about walking is that if you do the technique
correctly and put as much effort into walking as you would running,
you can get the same aerobic benefit. You are moving almost every part
of your body.”