Need help making a mantra to keep myself calm under extreme

A while back I took a like Java programming class and even though for the first hour things were going fine,once the teacher started clicking stuff and telling us what to do I was utterly lost.I felt way to nervous to try to ask him b/c it seemed to me that,that would obviously interrupt the flow of his lesson.Soon though I was having like a panic attack and burst into tears,with an onslaught off questions rushing to my mind about how I cant do this,why cant I understand this,what is he doing etc.

I withdrew the next day and the following day after that I meet with a counselor about this.He told me that I've got to make a mantra to keep myself calm.Days later I looked up what a mantra is and found out how their originally formulaic arrangement of words used as a chant or prayer in Hinduism but in the broader secular sense(which is what I'm going for here) there a truism like formulaic arrangement of words said repetitive.In both cases though their short.

Can someone help me make one or suggest one,please?.

Come on you are the best.