Q: While sitting, I had intense discomfort, but I let it be and it was okay. What happened?
A: In general, we deal with life by thinking, "Things should be this way," then fighting with things until they are that way, then fighting with things to get them to stay that way. Soon, our idea changes about how things should be, and we start over again. This might be called "Hating things to death." According to our skill, from this method may or may not come happiness dependent on conditions.
In the sit, it seems that you gave up on that strategy. You did not fight things. You let them be, or not be, without resistance and with open arms. In that way, you transcended them and they could be seen as empty. This might be called "Loving things to death." Out of this method certainly comes happiness independent of conditions.
Both strategies are valuable, but the former has finite value, whereas the latter has infinite value.