Jeff Galloway

“The label of "marathoner" has, from the beginning, been awarded to those who went the distance under their own power, whether they ran, walked, crawled or tiptoed. When you cross that finish line, you've entered an elite group. About one-tenth of one percent of the population has done it. Don't let anyone take that great achievement away from you.”
― Jeff Galloway, Marathon!

“By having at least one long run beyond 26 miles, you can boost your endurance limit, which will allow you to maintain a hard marathon pace for a longer time in the marathon itself. When you go the extra distance, it is crucial to take the walk breaks and adhere to the pacing guidelines. For maximum performance, your longest run should be 28 to 29 miles. And, I’ll say it again: you must go extra slowly on those extra-long runs. Walk breaks Take walk breaks every mile, from the beginning, to reduce fatigue. Put in a 1-minute walk break every 1–3 minutes of running from the beginning. Walk breaks do not reduce the endurance value of the”
― Jeff Galloway, Marathon: You Can Do It!