Two aspects come to mind: I love what I'm working on, and I love whom I'm working together with.
Working at Google means you work on solutions for problems that haven't been solved yet, and perhaps are not well understood yet. Every day is a challenge - a challenge I enjoy - and with these challenges I grow both personally, as well as technically.
But equally important, I thoroughly enjoy working with my colleagues. Everyone is smart, can take and will give feedback, and is happy to share knowledge. We've got a very relaxed atmosphere here, which also helps lots in simply being able to be yourself and performing at your best.
My work is part of my self-fulfillment. The other part is of course more personal, be it about spending time with friends and family, or pursuing my hobbies. It's great that my job gives me the flexibility to enjoy that just as much.
Naturally, my university education (MSc) provided me with the basics, which I now apply in my job. But what is taught at university courses isn't all you need. For example, I learned to program almost exclusively in my free time, co-developing an OpenSource online game. And I engaged in university life, furthering my organizational and leadership skills. Having said that, I did not pursue these things, because I was thinking about my career, but because it was fun and an adventure I didn't want to miss. :)
Give it a try. Don't let yourself be influenced by preconceptions you or others may have. You may be surprised by how often they differ enormously from the truth.
I almost didn't choose this career path, because of what others told me and how the subject was portrayed. Only when I started exploring computer science myself, did I discover how much it had to do with creativity, working with others, and ultimately making an impact on society.
Yes, it is hard work - but work that I genuinely enjoy, and it would have been a shame had I missed out on it. And who knows, perhaps you'll feel the same passion for this area once you give it a try!