The Gemara relates a story where a man told his wife that the Get she receives now will only be valid if he does not return within thirty days. The man came on day thirty but was on the other side of the river and could not cross. The man yelled from the other side saying "I'm here, I'm here!". Shmuel ruled that it doesn't count and the Get is still valid. Rashi explains that even according to those who say "Yesh ones b'gittin" there is an excuse of extenuating circumstances even with regards to a Get, that is only if the extenuating circumstance is unforeseen. In this case he should have realized he might not be able to cross the river and should have said the Get is also invalid if he standing by the other side of the river.
This teaches us an important lesson. So many times we find ourselves with an excuse why we did or didn't do what we should, and we say to ourselves that we had no choice. Almost all of the time the excuse could have been foreseen, and we could have prepared for that, and didn't!