To get a master's degree in computer science at my school, you have to choose a concentration area, like networks or artificial intelligence. I had some interest in the systems concentration, partly because it would give me a course background that would be very helpful if I decide to pursue a Ph.D.
As part of our orientation for new grad students, one of the professors talked to us about the possibility of doing a directed study with him on compilers (don't worry if you don't know what compilers are; just trust that they're an important topic in computer science, especially in the systems area). This professor also mentioned that this would probably be our best chance to study compilers early on, since the formal class on compilers is typically cancelled due to low enrollment. So, as soon as orientation was over, I naturally high-tailed it over to this professor's office. Paperwork was filled out, and I was signed up for this directed study.
Fast-forward a little over a month. Compiler stuff is hard. Another course that I'm taking in my concentration has proved similarly head-spinning. It was starting to look like my choice of concentration was a bad idea.
So I went to our weekly meeting for my directed study feeling down. I hate to fail at anything. I wondered if this would be total gibberish to me like some of the reading had been. Surprisingly, I was able to follow enough to hang on, and I had an epiphany: if I quit on this, I'd just be taking the easy way out and selling myself short again, which I totally have a tendency to do.
Not this time. If I have any hope of proving myself worthy to run with the big dogs, I need to challenge myself. During my first degree, I made the mistake of taking the easy way as much as possible, and I paid for it for a very long time.
So, approximately a month into my grad school career, I've had my first serious gut check. I have responded by kicking it in the pants and officially declaring a systems concentration (my directed study prof is happy to serve as my official advisor). That way it knows I mean business. I will do whatever it takes to succeed.