Learn something positive from the experience and move on.
Answer:
I would say washing your hands.
Explanation:
It depends on what pathogen is being transferred, but most contact with people is done through hands (handshakes, hugging, etc.), so washing hands constantly with anti-bacterial soap kills any germs that you may collect throughout the day.
Lactic Acid.
During exercise your muscles produce lactic acid. It's a metabolic byproduct that makes no contribution to exercise performance. It causes muscle fatigue and post-exercise muscle soreness.
