What are good strategies for not losing sight of the novelty and nontriviality of one's work? I would like to ask this community for help in finding good strategies for avoiding an aspect of my mindset that I don't much like, which I get when I've been working on a given project for a while - I begin to lose track of how novel and nontrivial the work is, sometimes leading to full-on crises of confidence in my work and, in bad cases, in my capabilities.

This happens to me once I'm rather deep into the project, around the stages of writing it up, defending it in correspondence with referees, and preparing presentations on the subject. (To anchor things a bit, I am a theoretical physicist working on analytical approaches in quantum mechanics.) In the initial stages of the project, and particularly at the times I have significant breakthroughs of either a technical or a conceptual nature, the elation and thrill of discovery will carry me a long way, and I end up building quite elaborate conceptual and mathematical structures that I am quite pleased with.

However, as a result of the familiarity that comes with using those initial breakthroughs over and over again, after some time they begin to 'flatten' in my mind as just regular features of my work, and the nontriviality of the tools I've built begins to wash out as the pains I felt when building them begin to fade into the distance. This is a version of 'familiarity breeds contempt', though maybe contempt is a bit too strong - it's just the over-familiarity that's the problem.

Now, this isn't really burnout, as this doesn't impact my day-to-day motivation to work or the energy I have to do it, and I continue to have interesting questions to work on and interesting answers for them. However, when I'm building a case for my work, particularly in writing, I find it hard to muster enthusiasm about the initial building blocks (usually the key advances in the work, particularly as perceived by an outsider) and to see them as anything other than well-trodden ground and everyday sort of fare. I know that it's because that's the ground I tread on every day, and that no one else does thus far, but it still impacts how I write about those tools and it makes it harder for me to present them with their full impact on the field.

I know that to some extent this sense of 'flattening' comes from the fact that as time goes on, I often find simpler routes to the results and tools of interest, and I know at an intellectual level that the existence of those simpler routes does not negate the effort it took to find the first one. That is, a result X that took months to understand can also be seen by spending a modest amount of effort building Y and then you "just add Z", but that still doesn't mean that the result is obvious to outsiders, and I know that the wholesale replacement of complex machinery for simpler tooling is also an achievement by itself. However, at a gut level, I still struggle seeing the result X in its full nontriviality, and it keeps flattening into just a trivial consequence of Z.

Moreover, I also have a good deal of objective evidence that the results are new and nontrivial, particularly in the fact that if I meet someone and walk them through the work, then the sheer amount of time it takes to go from baseline through the problem and tooling and up to the main results tells me that the material is indeed nontrivial, even after the simplifications. Similarly, the positive feedback I get in those situations tells me the work is worth its salt. However, that often lodges at an intellectual level but fails to register too much at a gut level of emotional handling.

I hope I've been able to describe this mindset sufficiently well. If nothing else, I would like the reassurance of knowing that I'm not the only one that faces this, but more importantly, I would like to know how folks with more punches under their belt handle this kind of situation, and what strategies I can try to regain an outsider's view of how novel and nontrivial my results are.
You are not the only researcher who experiences this. Certainly I personally also do.

It sounds to me like your question is whether these feelings of overexposure to your own work are: 


pathological--the result of some psychological process which makes you feel disenchanted with your old papers, regardless of their actual merit--or:
simply accurate--that is, as time passes, you come to have a more accurate appraisal of your own papers.


You already have suspicions about which of these two possibilities is actually correct. Personally, I try not to second-guess my own negative feelings about myself, so here is a strategy which I have found totally avoids the need to decide between possibilities #1 and #2: by working on a massive, multi-year, very ambitious project which requires many, many papers to develop, explain, and "make good on", I find that my feelings of overexposure about my own old papers, my own looking-at-my-old-papers-and-immediately-seeing-everything-I-could-have-done-better, those feelings are overcome by my excitement for the future of this broader long-term project and the small piece of that project that each of those imperfect papers puts into place. Being able to say to myself "I wish I would have written that old paper more elegantly, or proven this stronger result," or whatever, these feelings are washed away by the feeling of "That paper, no matter how wretched and ugly, still allows me to carry out the next step in the broader project," and then I can live with having written it. Maybe this approach can work for you too.