At this point of time, I WAS certain that software industry IS not where I want TO BE. Neither the advertising agency. I wanted to practice this lifestyle and learn many things. So, I submitted my resignation in December 2013.
I mean - I was certain (at some stage of my past) that Software and Advertising are not the industries in which I would want to look myself in(in future).
So, the sentence in italics needs to be corrected accordingly.