This is important for beginners. If you decide to start running, run for 10 minutes for the first time. Then increase the time gradually until you get to forty minutes of running. If you calmly run for forty minutes without stopping, then everything, you can switch to taking into account kilometers, distances, speed, pace, and so on. If you immediately start thinking in kilometers and, God forbid, compare your first race with a marathon, it may seem to you that all this is an empty idea, that it is impossible.