Sri Chinmoy: It is always good to have easy and hard days. It is best to have two easy days and then one hard day. Even having alternate easy and hard days is not good enough. If you run fifteen miles one day, it is not good to run seven or ten miles the next day. Instead, on your hard days cover twenty or twenty-five miles or even a full marathon. Then take two easy days. In this way, you can cover seventy or eighty miles a week.
Only those who are very strong and who are seriously training for long-distance running should do more than seventy miles a week. They can run one hundred miles or one hundred twenty miles. Otherwise, to run more than one hundred miles a week is useless.