You only need one bad experience to learn from it.
This is something that I have been starting to understand as a human being and a psychology professional.
It turns out, going through one event can completely change the way you see the entire world for the rest of your life. I think a lot of us can understand this in regards to violence or painful traumas. However, it actually takes much less than a massively shocking event to change your behavior forever. For instance, it only took my brother 1 long, exhausting day as a heating and cooling technician to forever change his daily routine. On one of his first days after eating as a professional HVAC worker for the local heating, cooling, and air quality control dealership, my brother was sent to some extremely difficult heating and cooling system repair jobs. He was already nervous enough about demonstrating his recently earned heating and cooling certification for real residential HVAC clients… and then the HVAC dispatcher sent him to the most difficult air conditioning and furnace repair jobs of the day. My brother got stuck at each HVAC appointment for several hours longer than he expected. The next thing he knew, he had been working a 14-hour day and his brain and body were in complete exhaustion mode. He was so tired when he left the last air conditioning repair service that he nearly fell asleep behind the wheel of the HVAC truck. To this day, my brother is prepared for long, arduous HVAC repair services. He always keeps an extra mug of coffee and a handful of caffeine pills in his heating and cooling repair truck.