"Carried Away" by Thoughts or "Choosing" Thoughts?

 During my lunch break today, I had a reflection about to what extent I believe that I am a "prisoner" to my thoughts. I think that one of my weaknesses in life is that I get carried away in negative thoughts, such as "I can't manage all these responsibilities", and these thoughts have a tendency to bring my energy down or lead me to stop reflecting altogether. It's as though my mind has already bought into a view that I am not able to go beyond a certain capacity...when in fact this too is nothing more than a thought! The inertia that people sometimes feel when they have many responsibilities at work may itself just be another creation of the mind. In telling myself that I have a lot to take care of, I give myself the false impression of a limitation, when in fact, I am not really that limited in what I can imagine myself doing or in setting goals for myself.
  I think one of the most important skills that one can acquire is not being emotionally involved in stress: that is, to "keep one's head" and to be present when one feels burdened by thoughts and heavy emotions in the body, particularly tightness and tension. It's helpful to recognize that everything is just a thought, and nothing more. On my way to work this morning, for example, I had a worrisome thought about whether or not I would have enough experience to tackle the work related project testing. Am I enough? the thought seemed to say to me. But then I paused to consider whether there is ever a point where a person simply says, "well, that's it, I have nothing new to learn here...I might as well go home and curl up in a ball". Sometimes this is what a person might want to do in certain circumstances, but does it happen all that much in real life? The point is that sometimes what appears to be a logical response to an uncertain situation might actually be an unlikely scenario. This is one of the problems that comes with "overthinking"; the tendency to imagine extreme scenarios, similar to the donkey who can decide whether to eat or drink because it is partway between food on one side and water on the other in a desert. What if there are times when I know what I am doing, and in another second I simply don't? Am I able to be both knowing and unknowing in the same situation, and be able to bear those in one moment?
   This comes to the topic of my entry: is it possible that thoughts control us, or are we actively choosing our thoughts at every moment? While I tend to agree that thoughts are a choice, I also believe that changing thought habit patterns is not easy. There is a certain inertia there, similar to when a person chooses a path that is already trodden in the snow rather than creating one's own path. It's simply easier to do what one has been doing all along; and it's equally easy to settle for a glib view that I can change my mind simply by adopting a new sentence in my mind. This is hardly convincing because changing one's mind is a project: it's something that requires a lot of passion and curiosity to explore what works and doesn't work. It's not likely to discover that one's mind is programmable like a computer, but it seems possible to treat thinking as a kind of adventure in beholding new possibilities.