The following are the types of threats that can cause stress and the feelings associated with it:
You feel that you have no or very little control over the situation.
Something completely unexpected happens or you cannot know in advance what will happen.
Something you have never experienced before takes place.
Your skills and ego are put to the test or others question your abilities.
Examples
Are the following situations familiar to you?
Control: You are late for an important appointment and are stuck in a huge traffic jam. You plan a visit to the zoo for weeks and your kid comes down with a stomach flu the night before going.
Unpredictability: You hear that the staff at your daycare are going on strike but you don’t know when. Your boss has mood swings and every day brings a new surprise.
Source: https://humanstress.ca/stress/understand-your-stress/sources-of-stress/