I see wearing a mask in a similar light to washing my hands. It is possible to be a carrier of an infection without having any symptoms yourself, and it doesn't hurt to wear a mask in certain spaces such as crowded streets, hospitals, shops, and public transportation where there are a lot of people. There could be people around me who are immunocompromised, and if wearing a mask will help prevent others from getting sick, that makes it all worthwhile! It's a small thing that can go a long way!