Deep breathing, abdominal breathing, alternate nose breathing can boost your immune system to protect you from any disease. Your thoughts, your inner conversations, your beliefs are creating the inner environment and that is where the cells thrive in positive environment. Everyone is forced to save himself or herself now, as against they were busy saving the world while ignoring the health of their own physical and mental health. 
I always said, Nature is the ultimate teacher! Now take care of the inner and the outer is taken care automatically! 

Love and light!