The bigger things and the little things.
I try to live my life as a minimalist, I like having very few things, and when ever I make the decision to get rid of something that I clearly am not using nor will I, but rather I was just holding on to it because I wasn't ready to let it go, I get a great sense of accomplishment.
Because I managed to do something that I believed in, even though it wasn't the easiest thing to do.
In my work, when I finish a project that I really invested my time and energy in, I also feel accomplished. Though, this does usually happen mainly with my personal work rather than my actual day job, since my personal work is far closer to me and, well, more personal. The feeling of accomplishment is much greater.
So really its the things that I succeed in and that are close to me that give me the feeling of being accomplished.