Should I let a bad mark from 10 years ago discourage me from taking on a TAship? 10 years ago it was my first year in University and I bombed a course in programming. I had no programming experience and was competing with people have been programming since 10. I felt stupid and my confidence crushed back then.
Since then I have done much more programming in a variety of settings, worked in industry on software projects, and created many projects using various programming languages often under deadline.
I have now returned to school and I am deciding to TA a course on the very same subject I bombed in 10 years ago.
However, I feel discouraged given my bad performance in this course. I feel like I still don't deserve to help to teach young people. I feel that other people are much more qualified than me even though they may be much younger. Plus I am also questioning if I actually know the concepts. Logically, a lot of the things I know and done are transferable, but I can't get over my self-doubt.
In this situation, should I decide to TA this course or not?
This is ultimately a personal decision for you to make and it's likely that the question will be closed.
I assume that you now have adequate background to be a TA for this course, so you've overcome the difficulties that you had when you first took the course.  Let me suggest to you that your experience in struggling with this course as a beginner is something that can help you in working as TA for the course because you'll understand how the students are sometimes struggling with the course.