I have been familiar and comfortable with regular expressions (regexes) most of my career. My first full time job after college used Java, and although I needed to use regexes I didn't have much in the way of mentoring or tooling. So, I kinda fumbled my way forward and learned gems such as highlighted here. I moved companies and eventually languages from Java to Ruby. I soon discovered Rubular which is an awesome tool for testing out and iterating on regular expressions. Still in the Ruby space, my next job was in security working with a team creating a scanning engine. Our use of regular expressions there was extensive, and put me in a place where I feel extremely comfortable with them.
Fast forward several positions and several language changes, I find I use them less often than I once did, but enough that my former experience has been invaluable. However, the main thing I wanted to capture was a tool a co-worker of mine introduced me to today, RegExr. I haven't used it much yet, but what little I've seen has been very impressive.
Also, a related and rather fun game.