Tl;Dr version: Pavlovian conditioning can cause humans to unconsciously flinch from even thinking about a serious personal problem they have, we call it an "Ugh Field"¹. The Ugh Field forms a self-shadowing blind spot covering an area desperately in need of optimization, imposing huge costs.

A problem with the human mind — your human mind — is that it's a horrific kludge that will fail when you most need it not to. The Ugh Field failure mode is one of those really annoying failures. The idea is simple: if a person receives constant negative conditioning via unhappy thoughts whenever their mind goes into a certain zone of thought, they will begin to develop a psychological flinch mechanism around the thought. The "Unhappy Thing" — the source of negative thoughts — is typically some part of your model of the world that relates to bad things being likely to happen to you.

A key part of the Ugh Field phenomenon is that, to start with, there is no flinch, only negative real consequences resulting from real physical actions in the problem area. Then, gradually, you begin to feel the emotional hit when you are planning to take physical actions in the problem area. Then eventually, the emotional hit comes when you even begin to think about the problem. The reason for this may be that your brain operates a temporal difference learning (TDL) algorithm. Your brain propagates the psychological pain "back to the earliest reliable stimulus for the punishment". If you fail or are punished sufficiently many times in some problem area, and acting in that area is always preceeded by thinking about it, your brain will propagate the psychological pain right back to the moment you first begin to entertain a thought about the problem, and hence cut your conscious optimizing ability right out of the loop. Related to this is engaging in a displacement activity: this is some activity that usually involves comfort, done instead of confronting the problem. Perhaps (though this is speculative) the comforting displacement activity is there to counterbalance the psychological pain that you experienced just because you thought about the problem.

For example, suppose that you started off in life with a wandering mind and were punished a few times for failing to respond to official letters. Your TDL algorithm began to propagate the pain back to the moment you looked at an official letter or bill. As a result, you would be less effective than average at responding, so you got punished a few more times. Henceforth, when you received a bill, you got the pain before you even opened it, and it laid unpaid on the mantelpiece until a Big Bad Red late payment notice with an $25 fine arrived. More negative conditioning. Now even thinking about a bill, form or letter invokes the flinch response, and your lizard brain has fully cut you out out. You find yourself spending time on internet time-wasters, comfort food, TV, computer games, etc. Your life may not obviously be a disaster, but this is only because you can't see the alternative paths that it could have taken if you had been able to take advantage of the opportunities that came as letters and forms with deadlines.

The subtlety with the Ugh Field is that the flinch occurs before you start to consciously think about how to deal with the Unhappy Thing, meaning that you never deal with it, and you don't even have the option of dealing with it in the normal run of things. I find it frightening that my lizard brain could implicitly be making life decisions for me, without even asking my permission!

Possible antidotes to Ugh Field problem:

Actively look out for the flinch, preferably when you are in a motivationally "high" state. Better still, do this when you are both motivationally high, not under time pressure, and when you are undertaking an overview of your life. This overview exercise will tend to make your mind range over all of the relevant parts of your life, and hopefully "throw up" some "Ugh!" reactions.
Concretely visualize how your life could be much better if you oust control of it from your lizarrd brain. Imagine, in near-mode, how much better your future life could be if you can find and "pick off" your Ugh Fields and optimize the relevant part of your life. If you haven't yet identified these areas of your life, imagine that some concrete good thing (such as eating ice-cream, laughing with friends, etc) will happen to you in the future if you can honestly face these areas.
Identifying these reactions, writing them down in a list, and affirming that you want to take control of them will help you to distance yourself from them. Once your conscious mind has a positive desire to take control, the offending stimulus will hopefully activate this "take-control" reaction, rather than the "flinch" reaction. Key to this is framing the "take control" action as a "positive" outcome enabler will facilitate action, as Kaj and PJ have already told us.

1: (Credit for this idea goes to Anna Salamon and Jennifer Rodriguez-Müller. Upvotes go to me, as I wrote the darn article)