heat.

Reactions from heat:

1. The egg - after being boiled, the egg becomes hard. 

Starting with a meek heart, tough situations and circumstances cause one to become hardened and stiff.

2. The carrot - after being boiled, the carrot becomes limp.

Going in strong, headfirst into the situation, one soon becomes disillusioned and loses all resolve.

3. The coffee bean- after being boiled, disperses flavor and aroma.

Just like the bean, they allow tough times to run their course, but also causes them to change their environment through their experience.