The best way to be really ill with viruses and bacterial infections is to protect yourself from them, so that your immune system, so to speak, gets flabby and lazy from lack of exercise dealing with new illnesses and if you do get anything, you are more likely to get it badly.
The evidence world wide has been that masks do not stop you getting COVID or anything else, merely slow progress of the disease down.
I caught COVID last year and simply stayed at home until I had 2 clear tests. DH had it at the same time, but was over it faster.
The best protection against flu, COVID, or any other bug you may get, is to look after your health, eat sensibly, keep your weight down and take plenty of exercise.
I thought the main reason masks were worn in countries in Asia, was to protect people from air pollution, not infection.