Sri Chinmoy: If it is unbearable, excruciating pain, then something serious might happen. But if there is just a tiny pain in your foot, this kind of fear is only false anxiety that is coming to your mind. If you are worried, you can take rest for a few days and see if the pain goes away. If it leaves in just a day or two, you will know that it was nothing serious. In this way you will become more confident that nothing will happen to your foot if you run.
So if the pain is not that serious, you do not have to worry. Your foot is not going to give out. It is only that fear has entered into your mind, and the mind has created false anxiety in you, a false alarm. You should not cherish these fears.