the thing is, you should wear one in public. it is out of respect to the other people. it is not designed to protect you from others. but it is a sign that you want to protect others from you. even though you think you are not infected, it puts others at ease to know that you have a mask on. if i see you out without a mask, i will ask you to either leave the store or put a mask on. or i will get management to do it. how do i know you are not infected? you maybe asymptomatic and could be spreading the virus without knowing it.
now if you are in your car or something, you do not have to have a mask. but in a store, restuarant or any closed environment, please where a mask.