The sentence you have probably been told

Anxiety is a sign of weak tawakkul. If you really trusted Allah you would not feel like this.

It gets said in masjids, in family kitchens, and in comment sections, and it gets said by people who mean well.

Be exact about what is wrong with it, because this course is not going to overstate its case to make you feel better. There is no text that makes how anxious you feel a measure of how much you trust Allah. People do write otherwise, and some of them will quote something at you, so nobody is claiming the sentence was invented out of nothing.

What follows is what the Qur'an itself does with fear, which is something close to the opposite.