• Avoid drugs (e.g. marijuana, alcohol, tobacco, caffeine)
• Get enough sleep (i.e. wake up naturally; no alarms)
• Regular exercise (primarily playing sports)
• Eat healthily (avoid sugar, avoid starchy food, eat lots of fatty meat and eggs)

I started wearing a mask in crowded public places in about 2020 (for some inexplicable reason). I never stopped. I wear one in the metro. On buses. In crowded shopping malls (or even crowded small shops).

I used to get several colds per years and maybe one thing that caused me a fever each year (usually a flu).

I haven’t had a cold or flu or any kind of fever-inducing infection since … oh … call it 2020.

Avoid children

Being an introvert and maintaining a healthy diet.