果汁儿为啥流啊流？
Heidi 博士在本书中特别喜欢用 juice 这个词
不过在这里 juice 不是果汁儿，而是能量的意思
比如在下面的句子中：
You want to challenge yourself and set the bar high, because challenges really get the motivational juices flowing, while avoiding goals that are more or less impossible.
Vigilance actually increases in response to negative feedback or doubting yourself. There’s nothing like the looming possibility of failure, the very real likelihood of danger, to get your prevention juices flowing.
In fact, a touch of pessimism is probably what will serve you best—there is nothing like the very real possibility of danger to get your prevention juices flowing.
It is true that, for some goals, believing you will succeed really gets your motivational juices flowing. But notice that I said “some” goals.