Chase Jarvis believes that people create photographs in order to share them, and that there is a difference between personal work, and other work. So that, even if you are a professional photographer, most of what you do will be for money and not for the sake of art. This is the sustain part, if you are not a professional photographer maybe you sustain yourself by having
Coming up with new ideas, designing experiments to test them, and then to run those first experiments, when the method starts working and you get the first indication of whether you can reinforce or disprove your hypothesis. That's the essence of science, and that's where all the excitement lies.
Publishing is obviously the all-important sharing in science, but it being all-important also puts it firmly in the sustain-phase. Pleasing that third-reviewer, completing those control-groups and trying to fit three years of work into a 250-word abstract is not something you do for fun. The fun part of sharing, the part that actually lets you share your insights, get feedback and learn new stuff, is conferences.
That is where you can (not everyone does, but they could) present your really new data, and hint at ideas for the future and see how your thinking is received by the community. It sharpens your thinking, and brings the field forward. It will often reveal experiments that have already been done but not published, and might warn you off (or reinforce) some particularly difficult hypotheses.
Somewhere in each project's life it goes from being curiosity-driven to being driven by the need for completeness before publishing. Coincidentally this is where it often gets boring, which is why I put finishing up and publishing under the sustain phase. The other thing that is directly science-related that is part of sustaining is grant-writing, and grant-reporting. It is a bore and it takes a huge amount of time, but it is necessary to continue doing research.
Otherwise, sustaining often means teaching, supervising students and treating patients. If you are lucky, you find all of this exciting and entertaining as well, but even if you do, it is time off from research. However, just as in photography this is not only what often pays the bills, it is also a fountain of ideas for future research. Sometimes a question you can not answer may indeed be an unanswered question, and the problems that bother actual patients (or their physicians) keeps you founded in clinically relevant research.
So, there we are. Do some proper work, write some grants so that you can do research and go to conferences where you can