The main thesis of PJ Eby's Thinking Things Done is that the primary reason why people are incapable of being productive is that they use negative motivation ("if I don't do x, some negative y will happen") as opposed to positive motivation ("if i do x, some positive y will happen").

FWIW, my model has been refined a bit since then, and is actually a lot closer to Halvorson's model than it would appear on the surface; a self-image component really is required to make it "push" motivation in my definition.

One of the problems with using one's self as the main test subject is that if you have a systemic bias you can't spot it. At the time of my original writing, I'd have been hard pressed to identify a motivation of mine that wasn't driven by some sort of self-image/"be good" issue. ;-) (So, I implicitly assumed the image component, and taught it in practical coaching, but didn't really include it in the explicit model so much.)

Pretty much all the problems I've lumped under the description of "naturally struggling" or "self-defeating behaviors", though, I would now unpack as "patterns of negative self-reinforcement, usually based on inaccurate (and unconscious/implicit) assumptions or beliefs, mostly including a presumption that the self is inadequate or defective in some way, and must change itself or perform up to some standard, in order to mitigate the believed defect or inadequacy."

But as you can see, that's not nearly as catchy as "push vs. pull motivation". ;-)

It is, however, probably the most accurate expansion of what I mean by "push motivation", both then and now (in the sense that the description still applied then, even if I didn't grasp anywhere near all the subtleties yet). And the "negative self-reinforcement" part is actually more relevant to how it's harmful, even if those negative self-reinforcements are caused by the "push motivation". I think even Halvorson has alluded to this in her discussion of "be good" motivation: i.e., it leads to people making themselves feel bad even if they're actually improving at something.

To put it another way, I've come to realize that the harms of "push motivation" aren't just in its stressfulness and inherently variable level of motivation, but that it also causes one to negatively reinforce the very behaviors (such as learning, practicing, trial and error, etc.) that would actually address the problem one is ostensibly trying to solve. I now believe that these negative reinforcement patterns are the direct cause of a substantial amount of "meta akrasia", in the sense that it makes people less likely to continue even interventions that work, or avoid starting interventions that would work, if only they would actually try them. (Certainly, it tended to make me rule out huge categories of possible approaches to my problems, for all sorts of spurious but seemingly valid-to-me reasons.)

So, yeah, it's all about identity, but it tends to be at the level of basic perceptions of self as lovable, capable, contributing, etc., underneath the object level of "business person", "jazz lover", etc. With the relevant level being implicitly-acquired beliefs about what certain attitudes, behaviors or characteristics "mean" about a person's lovableness, worthiness, etc.

As you say:

If you're someone who is lazy and isn't accomplishing much in life, perhaps depressed, then it makes intuitive sense to motivate yourself by saying "Come on, self! Do you want to be a useless failure in life? No? Well get going then!" But doing so will accomplish the exact opposite and make you feel miserable.

But the reason for this has little to do with object-level identity, as you propose, and everything to do with one's "rules of self-worth", as it were. Identity can be a powerful force for positive motivation, provided that the identity isn't one that you're adopting in compensation for a perceived low self-worth. In particular, the motivation towards consistency that identity provides can be a powerful precommitment tool.

That being said, in the past I'd have agreed with you that it's bad and dangerous; even now, I would be very selective in how I promote its use. If the person using it doesn't realize their current self-image is built on denying the worthless self they're afraid they are, then, as the saying goes, "you're gonna have a bad time."

Also, in the general case, identity-based consistency motivation shouldn't be confused with a "be good" goal: it's an expression of "being yourself", in the sense that if you see yourself as somebody who helps people, you're more likely to behave consistently with that identity, at least when other people can see and the identity is primed. In the case of a "be good" goal, however, the actual identity is that you're not good (in whatever way is relevant), and thus have to perform to a certain level in order to escape the undesired identity. That is, the self-definition of yourself as "good" is a fake, an aspiration intended to compensate for the perceived lack.

So it's okay to have an identity; the problem is trying to have an identity you don't think you inherently have, but need in order to be worthy... which not-so-coincidentally lines up with all the "not being yourself" examples in your post. ;-)