I had been sedentary for a few months and decided to get in shape. Since a few years ago, long before the days of the internet, I had a dream in which I went six miles alternating walking and jogging, first a mile jogged then a mile walked and so forth I resolved to put into practice what I had dreamed and began doing the six mile jog/walk every day. What I experienced was incredible pain in the calves while jogging, having to take tiny steps while jogging, and being unable to jog faster than the average walker; and I was tired all the time as a result of my efforts. I could not get the six mile jog/walk done in less than two hours. After a few weeks of the jog/walk I became sick, fatigued with a bad cough for a couple of weeks. After being sick when I returned to the track I just walked the six instead of jogging the first and then every other mile and have not gotten back to jogging since. But I have gotten my time down for the six miles which was stuck at between two and two and one half hours whether or not I jogged half the miles down  to about one hour fifty minutes.
What went wrong? I began researching the six miles jog walk on the internet after I got the time down to one hour and fifty minutes. I found a commentator who stated that once you are able to walk four miles an hour, you are ready to start jogging. Four miles an hour would mean walking the six miles in 1.5 hours. So if this commentator is speaking truly, I attempted to jog before I was ready to jog and this caused the problem.
It makes training more interesting and productive to know competitive statistical facts related to the training. How fast do the fastest walkers walk six miles? I calculate that Olympics walking record holders would be able to walk six miles in 38 minutes 42 seconds (male) and 40 minutes 34 seconds (female). These Olympics walkers walk using a style of walking different from that normally used by persons when they walk.
Below I have compiled some quotes and facts regarding walking:
"Unhappy businessmen," declared Bertrand Russell, "would increase their happiness more by walking six miles a day than any conceivable change of philosophy,"
When it comes to aerobic conditioning, the time and intensity of your exercise session combine to produce a training effect.  For example, if you walked for two hours at a 20-muinute per mile pace, you would cover six miles and use about 600 calories of energy.  On the other hand, if you ran for 40 minutes at a seven-minute per mile pace, you would also cover almost six miles and use about 600 calories of energy.  The exercise outcome is essentially the same, and I submit that the person who runs six miles in 40 minutes will hike longer and stronger than the one who walks six miles in two hours  --
Perhaps you are presently capable of walking three miles in one hour.  Begin with this and progressively increase your walking pace to 3.25, 3.50, 3.75 and 4.00 miles per hour.  Such improvements should be possible on a week to week basis if you walk three to six days per week. Once you can comfortably walk four miles in an hour, you may start jogging. 
Here are some pre-race (walking) tips from Herm, and other top walkers: Have a very light, carbohydrate-rich meal, such as dry toast, and a Powerbar or a piece of fruit 2 to 4 hours before your walk. --
Each mile walked burns about 100 calories. --

A good rule of thumb for cycling times or distances is to use a ratio of 3:1 as cycling is three times as efficient as walking. If you expect pedestrians to walk two miles without difficulty then they will be able to cycle six miles. If a route can be comfortably walked at 3 mph it can be ridden at 9 mph. --

Of all exercises walking is the best. –THOMAS JEFFERSON, Third US President (1801—09), 1743—1826 --

Walking is the best possible exercise. Habituate yourself to walk very far. The Europeans value themselves on having subdued the horse to the uses of man; but I doubt whether we have not lost more than we have gained, by the use of this animal. –THOMAS JEFFERSON, Third US President (1801—09), 1743—1826 --

Take a two-mile walk every morning before breakfast. –HARRY S. TRUMAN, Thirty-third US President (1945—53), 1884—1972 --

 never knew a man go for an honest day’s walk for whatever distance, great or small, and not have his reward in the repossession of his soul. –GEORGE MACAULAY TREVELYAN, British historian, 1876—1962 --

These men I have examined around the world who live in vigorous health to 100 or more years are great walkers. If you want to live a long, long time in sturdy health you can’t go wrong in forming the habit of long vigorous walking every day … until it becomes a habit as important to you as eating and sleeping. –DR. LEAF, Executive Health, 1977 --

Walking is man’s best medicine. –HIPPOCRATES, Greek physician, 460—377 BC --

And whether golfers would like to give their opinions on the Martin case or hold them to themselves, there are undoubtedly those who would tell you that sitting in a fancy air conditioned golf cart beats walking six miles any day -- or that it at least helps to reserve finite energy and prolong stamina. --

Mens - Walking Records - 20km
 Olympic Record (20km) (12.4 miles): 1:19.57 Jozef Pribilinec Cze 1988
 Olympic Record (50km) (31.1 miles): 3:38.29 Vyach Ivanenko Rus 1988
 2000 Gold Medallist: Robert Korzeniowski POL
 2000 Silver Medallist: Noe Hernandez MEX
 2000 Bronze Medallist: Vladimir Andreyev RUS
 1996 Gold Medallist (50km): 3:43.30 Robert Korzeniowski Pol
 Womens - Walking Records - 20km
 Olympic Record (10km) (6.2 miles): 41.49 Yelena Nikolayeva Rus 1996
 2000 Gold Medallist: Wang Liping CHI
 2000 Silver Medallist: Kjersti Plaetzer NOR
 2000 Bronze Medallist: Maria Vasco ESP

Kilometers to miles conversion: --