That's a good and non-trivial question and I liked Ravisuriya Eswara's way of answering it.
In this eye-opening read, Ash Winter convinces us why thinking about performance testing is crucial to successful project delivery. I especially liked how rich in useful references this article is, including tools, books and the dos and don'ts.
This is a great example of an honest self-retrospective by Bruce that can help recognise your strengths and fight your fears as a software tester. Huge respect for transparency!