When I was applying to colleges, my application essay was about how I wanted to be like Gregory House. I wanted to know everything, ask all the questions, find all the answers. I even wrote about how I wouldn't stop bothering my friend when he changed his first name from the shorthand version to the full version on Facebook. This necessity to know has long been prevalent - I also recall my AP Psych class and how I wrote down "not knowing" as one of my biggest fears. That could be as small as not knowing the answer to a question on an exam, as medium as not knowing why someone does the things they do (or why someone cares about the things someone else does), or as large as not knowing what happens to us after we die.
I've been proportionately afraid of those things over the course of the past 10+ years, but I'm finally starting to learn to let go. To acknowledge my fear, to acknowledge the uncertainty of a situation, and to let it go, and to come back to my breath and the present moment. It doesn't matter as much to me anymore why people do the things they do, or why people care about the things other people do. (Sometimes it still gets to me, though - nobody's perfect.) It still cares the hell out of me to not know what happens to us after we die, and to conceive of inconceivability, but that's always a passing fear. It leaves as easily as it arrives.
I'm still working on letting go of letting go, and the idea that telling people I'm letting something go still counts for as much. It doesn't. It still counts, sure, but not as much as it would if I simply let go of letting go. I suppose this is the higher-level state of consciousness that comes with years of practice of meditation (I still have a ways to go). In the meantime, I'll continue to be mindful of my reactions and turning them into responses. I'll be mindful of when I do let something go, and I'll be mindful of when I let something sit with me for longer than I want it to. I'll be mindful of letting go of letting go, acknowledging that, and coming back to the breath.
That's all we know we have.