The "Weight" of a Thought

   When the mind feels heavy or there is something weighing down on it, is it really the mind that is heavy? This is an interesting metaphor that would be notable to explore. For instance, we say, "a heaviness filled my heart", or "I feel a heavy weight on my shoulders", to mean that a person is overwhelmed or has too much happening at the moment. But I wonder, what is it that makes a thought 'heavy'? It can't be a physical weight (since thoughts don't have an actual measurable 'weight' to them), but then why do we experience some thoughts as being 'heavy' while other thoughts are considered 'light'?
   I think in a sense the 'heaviness' of a thought is often dependent on the time frame in which it has arisen in relation to a goal or a projected resolution. When I am first starting to do something, my thoughts about it are often jagged, raw, and full of complexities, in the sense of not knowing where the thought is going, or which path it will take eventually. Typically, with most problems, there are multiple causes and conditions which create the situation. Trying to somehow 'unravel' those particular thoughts can seem overly complex, because there are interlocking associations and connections surrounding that thought and what might have preceded it. It's only by examining the conditions as part of a whole that the thought can start to be revealed for its possibilities or for routes of action.
    In contrast, 'light' thoughts are usually the result of long processes of thinking, where one has resolved a lot of the previous causes and conditions that come to play in developing the situation at hand. They are smooth precisely because the other pieces in the puzzle seem to fit quite well, and there is not much need to adjust the situation.
   The point is: is there really any 'actual' distinction between these thoughts? I wonder if perhaps what makes a thought heavy or light is not the content of the thought itself, but rather one's attitude toward it. If I expect or even demand simplicity of thought at all times , then I am not being sensitive to the reality that thoughts can take a lot of time and effort to truly unfold. But the other point is that if I am able to see that the thought itself has no 'weight' attached to it, then I don't necessarily have to engage that thought in any way. It would be nice for me to clarify the thought in mind and learn more about how to handle the challenges arising in the thought, but perhaps it is not so necessary that I 'solve' anything in that thought. Letting the 'heaviness' of the thought be known rather than trying to make the thought into something else could go a long way in making it more manageable to deal with these kinds of thoughts.