> I've also always regarded myself as introspective enough not to be able to benefit from therapy.
Not the OP, but as an introspective person, I've found it was actually my introspection that predisposed me to benefiting from therapy. For me, my issues stemmed from negative self-talk, which is a misfiring of introspection. I would read the world and assign negative interpretations to how I was treated or how I messed up -- all the while subconsciously congratulating myself for being a self-aware person.
Therapy was a way for me to correct this misfiring feedback loop. My perceptions of the world may or may not have been correct, but the central idea is that I was assigning inordinate weight to the negative perceptions rather than the positive, which caused my emotions to spiral. This led to a pattern of catastrophizing.
Breaking out of that entailed a third-party grounding me and giving me more balanced interpretive options, and reminding me that my reading of the world was only one of many possibilities and not even necessarily a correct one (the limitations of introspection are sometimes astounding).
The part that's the most helpful about therapy was moving past interpretation, and employing positive techniques and taking action to deal with the world positively (doesn't matter if the interpretation was true or not). These actions encompass things like setting boundaries, or writing stuff down and interrogating them from multiple interpretive lenses instead of accepting them at face value. The act of taking action also helps dispel a lot of self-fulfilling prophecies. [1]
For me and likely for most introverts, negative self-talk is our weakness. Distorted introspection, while seemingly honest, is at the root of many negative emotions. It's very hard to fix feedback loops from within (since the thing you're using to fix them is the very thing that's broken) -- so engaging professional help is often very useful.
[1] An abstract example of this would be (not true of me, but to illustrate the point): Say I was passed over for a promotion and I start building narratives as to why. Maybe it's because I've been wronged in this way or that, or there's discrimination, or I'm not part of the inner circle. All of these things might be true (or not)... but if you think they're true and you respond unproductively by sulking, you're not going to make progress. Instead, you can change the framing and tell yourself maybe it's true, but let's give room to other interpretive options. Maybe it's because I don't really sell my ideas enough, so let's work on that. Maybe I'm really not ready so let's try upskilling. And the end result is that you move the locus of control from things you can't control to things you can control, which improves your overall well-being. And though there's no guarantee, because you've improved yourself in all these ways, your negative self-fulling prophecy might even turn out to be a positive one (but again, there's no guarantee). At any rate, by electing to deal with the world differently, your mental state improves, which causes you to present differently to the world. This in turn has the potential to start positive feedback loops.