Here you are using 'not used to' to inform someone that you are unfamiliar or uncomfortable with a topic at hand.

当你在这里使用'not used to'的时候，是告诉别人你对现在这个话题不熟悉或不舒服。

Here are some examples: 这里有一些例子： 

"I'm not used to talking English."

  我不习惯说英语。

"I'm not used to studying so much."

 我不习惯学那么多东西。

"I'm not used to being around new people."

 我不习惯身边有不认识的人。

"I'm not used to talking in front of groups of people."

 我不习惯在人群前面说话。

"I'm not used to having so much stress."

 我不习惯有这么大的压力。

"I'm not used to traveling so much."

 我不习惯经常旅游。

"I'm not used to working so early."

 我不习惯太早工作。

"I'm not used to having so much responsibility." 

我不习惯有这么多的职责。

"I'm not used to drinking so much."

 我不习惯喝这么多。