Anybody who's ever pursued publication knows about waiting. It's what we do after we submit. Wait. We distract ourselves with other tasks, including other writing, and we send out other submissions, etc. But on some level we're just ... waiting. Right?
The closer a manuscript comes to possible success, the harder the waiting gets. An editor asks to see a full manuscript based on a query. Or an editor asks for revisions. Or an editor says she's showing it to her editorial director. Each step of the way, getting through the time until you get the verdict is progressively more agonizing.
All the waiting is beginning to seriously wear on me. It's a bit like living in suspended animation all of the time. I've been doing it for years now, and I'm not sure it's a good thing for my mental health. It's hard to live in the moment when a part of you is caught up in anticipating/dreading what's around the next corner.
It's a separate phenomenon from having your hopes repeatedly dashed, which is tremendously hard to live through time and again. Waiting for feedback or a decision on a manuscript is holding your breath and getting a rejection is having the breath knocked out of you. Neither one is good for you.
Sometimes I wish I had an agent who could do the waiting part for me. Not even tell me where she's submitted or when. It might free me up to stay focused on the writing.
But of course getting an agent would mean more of the same. Research, query, submit ... wait.