How to stop feeling guilty about unfinished work? My biggest challenge as a PhD student is best summarized by the following from PHD Comics:

"Piled Higher and Deeper" by Jorge Cham
www.phdcomics.com


A consequence of working in research is that the end is never in sight - unlike other jobs, there is always more work for you to do. 

I am pretty good at making sure to take care of myself, because I know it's important. I can force myself to go for a run, get something to eat, participate in a regular activity that's not related to academia. But I can't turn off the voice in my head that keeps nagging me about the work that's waiting for me back at the office.

This is especially true when there are deadlines and people relying on me to meet them. On top of my research, I have mentees I should be spending more time with, students we won't be able to hire if I don't get my grant-writing act together, collaborators who keep asking when I'm going to write up that work we did together last summer. If I don't do this, nobody else will; it's not like a normal workplace, where your boss can reassign an important task if you are too overloaded to handle it.

So, my question is:


  How do you avoid feeling guilty about all the unfinished (and unfinishable) work in academia?


I am looking for specific, practical techniques based on research and/or personal experience, not suggestions that you just thought of but have never tried.

One technique I've tried with limited success is to make a daily to-do list that is limited to three items, and tell myself that I'm not allowed to feel guilty about not doing things that aren't on the list. It works when I'm not terribly busy... but most of the time it doesn't. 

Related questions:

How to avoid thinking about research in your free time is related, but I'm not trying to avoid thinking about research in my free time. I'm just trying to avoid feeling guilty about research in my free time.

Also related is How should I deal with discouragement as a graduate student? but those answers seem to address how to convince yourself that your efforts are worthwhile. I (usually) realize that my efforts are worthwhile, I don't know how to convince myself that I'm putting in "enough" effort (whatever that means).
tl;dr: Keep forgiving yourself and keep working.
I am having the same problem, and only recently it got better.
I have it only for open-ended work (scientific projects, other personal projects - everything which is of type &quot;I should have it done&quot; and the same time it is not closed; even worse when others are waiting for results). It seems to be very different from &quot;normal&quot; work (when someone gives me a particular task) and work with an expiry date.
The wisest (and most successful) piece of advice I found is this one (from Smart Guy Productivity Pitfalls - Book of Hook, which has more good points and is definitely worth reading):

6. Do not overpromise to make up for poor productivity.  There's a tendency when we're falling behind to try to overcompensate with future promises.  &quot;When I'm done, it'll be AWESOME&quot; or &quot;I know I'm late, but I'm positive I'll be done by Monday&quot;.  By doing those things we just build more debt we can't pay off, and that will eventually lead to a catastrophic melt down when the super final absolutely last deadline date shows up.  Just get shit done, don't talk about how you're going to get shit done.

Also, somewhat related is forgiving yourself for being not productive enough (constantly feeling guilty does not help; not only for me, but it seems it does not work for most of people):

The key finding was that students who'd forgiven themselves for their initial bout of procrastination subsequently showed less negative affect in the intermediate period between exams and were less likely to procrastinate before the second round of exams. Crucially, self-forgiveness wasn't related to performance in the first set of exams but it did predict better performance in the second set.

And from a bit different angle, from Elizabeth Gibert's TED talk on genius
(it's about treating inspiration, but it is similar for everything - no matter how good you are, you won't do everything; so why should you be bothered by missing a few things?):

And [Tom Waits]'s speeding along, and all of a sudden he hears this little fragment of melody, that comes into his head as inspiration often comes, elusive and tantalizing, and he wants it, you know, it's gorgeous, and he longs for it, but he has no way to get it. He doesn't have a piece of paper, he doesn't have a pencil, he doesn't have a tape recorder.
So he starts to feel all of that old anxiety start to rise in him like, &quot;I'm going to lose this thing, and then I'm going to be haunted by this song forever. I'm not good enough, and I can't do it.&quot; And instead of panicking, he just stopped. He just stopped that whole mental process and he did something completely novel. He just looked up at the sky, and he said, &quot;Excuse me, can you not see that I'm driving?&quot; (Laughter) &quot;Do I look like I can write down a song right now? If you really want to exist, come back at a more opportune moment when I can take care of you. Otherwise, go bother somebody else today. Go bother Leonard Cohen.&quot;

And from my personal stuff (I mean things that I found helpful):

using to-do list only for task (i.e. things I know I can do in a few hour max), not projects (it's depressing to have &quot;finish this paper&quot; on the same list for long months, cf. relevant PhD Comics strip),
underpromise and overdeliver to oneself; i.e. committing to do each day less task than expected (this way, with the same results, it's &quot;wow, I did things from the list plus 2 extra&quot; instead of &quot;I only made almost half of the first point out of 7&quot;; extrapolating one's maximal efficiency does not work...).