One thing about adulthood that way too many people learn way too late (and have no choice but to learn the hard way): you have to be deliberate/proactive about everything. For the first time in your life, you can't be passive participant in anything.
Recently, I was able to board a flight from a certain country to London and upon getting to the check in counter, I was told that there was a problem. They couldn’t board me because according to them, my UK visa (even though it was months from expiry) was no longer valid.