I wonder how you guys deal with regret?
Regret in the sense that you have done (or not done) something, that now can't be changed.
E.g. a couple of years ago I found out that I probably had to pay 1500 $ taxes if my income was over the threshold. I asked the accountant to calculate if this was so, and he told me that I was just within range. If I noticed in time I could lower my income and hours to stay under the threshold.
Now a couple of years later it appeared that my income was over the threshold and I have to pay the 1500$, which is quite a lot for a student.
Although I blame myself for passing on the matter to the accountant, instead of checking it myself, I feel that I get nowhere regretting my choice. I just don't think about it and accept it as given. Since there is little I can do to change things.