Sri Chinmoy: Your running capacity changes every day because every day you are in a different consciousness. One day you feel light. One day you feel heavy. One day you feel inspiration and another day you feel no inspiration. But once you have been running for a while, you will have developed a basic running capacity, and this capacity will determine how fast you can run even on your slow days. If you can run a seven-minute mile, then one day if you are not in a dynamic mood, you will go at a nine or ten-minute pace. You will not go at a fourteen or fifteen-minute pace. Even on your worst day, you are not going to run slower than a nine or ten-minute pace.
On a slow day, if you want to maintain the same joy that you have when you are running well, you can play a trick on yourself. Imagine that instead of being forced to run at a ten-minute pace that day, you decided to run at that pace. If you feel that you are compelled to run slowly, then you will feel that your freedom has gone away, and you don't want to be anybody's slave. But if you feel that it was you who commanded your body to go at a ten-minute pace, then you won't feel miserable. Right from the beginning, if you feel that it was your decision to run at that speed, you will be as happy as if you were running at a seven-minute pace.