ESL need a help :)

I made this response to the job interview question: What is your weakness which is impatience. Any help and criticism is welcome.

tend to get impatient at times when stressed out. XYZ Telecom was quite stressful environment I've worked in. I struggled dealing with stress back when I was in Canada due to large volume of unhappy clients. Our service wasn't competitive, the fact that we were just getting started that time and Engineers were making a lot of Technical adjustments that caused constant service interruptions. Over the course of months I had been so fed up so many times with stress I become impatient and just wanted to quit my job, but my ever encouraging supervisor had me motivated and reminded that I've done some of my best work under tight situations before where the atmosphere was more stressful and pressure only tests our ability. And finally, later that week our Service went back to normal and slowly the numbers of irate customers lessens as days gone by. I've learned that it was all about a matter of patience. I’m someone who should looks at what I can improve without being irritated.