Can you improve your stamina?
I run and walk during the 2100 meters. It takes more than 12:45 minutes to complete the distance.
I run and walk during the 2100 meters. It have finished in less than 12:45 minutes to complete the distance.
I can run the whole distance at about the same speed. And I did it in 12:45 minutes.
I can run 2100 meters in 11:00 minutes without stopping.
I can run 2100 meters in 10:00 minutes without stopping.
I can run 2100 meters in 9:00 minutes without stopping.