I remember thinking in college that I'd half-ass my coursework so I could go do a major open-source project so that I'd have a kick-ass resume when I entered the working world. The project was nowhere near as kick-ass as I hoped (I did the software for fictionalley.org), but it did serve 100k people or so, and I didn't have any trouble getting jobs. So that was something, at least.
Then I thought I'd work my tail off for a few years so I could found a startup and get rich. Well, I did work my tail off, and I founded a startup, but I just didn't have the skills yet to take it across the finish line. It didn't make me rich, it failed without accomplishment. But I did get hired by Google afterwards, and I guess that's a decent consolation prize. So that was something, at least.
And then once I'd been at Google for 9 months, I heard about this cool new project to completely redesign the search page from the ground up. At the time (2009), this was viewed as crazily ambitious: remember that the main Google SRP basically had not changed in look & feel since 2000. We launched in May 2010, after a long hard slog, and we felt really good about ourselves for a while. But then Google Instant launched that summer and completely overshadowed us, and the page was completely overhauled again in the summer of 2011, so the UI we slaved over lasted barely a year. We each got reputations internally as kick-ass devs that got stuff done, though, and were given a fair amount of latitude to pick our next projects, and had our pictures in BusinessWeek, and once in a while somebody even remembers the Google Search UI from 2010-2011. So that was something, at least.
I'm still looking for the big success that'll make it all worthwhile. I'm beginning to think that it doesn't really exist, that no matter how "successful" I am by external metrics, I'll always be chasing the next big thing. And increasingly, I'm beginning to think that the real big success was just the fun I've had hanging out with other people. That can sometimes be in the context of work, or it can sometimes be in the context of play. But somehow I think it matters a lot more than 80 hour weeks that usually go for naught anyway. (Luckily, I haven't really put in that many 80-hour weeks. In crunch time I might do up to about 60, but for the most part I work reasonable hours and spend my free time with friends.)