The verb reckon, says my dictionary, means to calculate, be of the opinion of, or be sure of. It comes from the Old English (ge)recenian, meaning "to count up."
At this time of year, when summer has given way to autumn, I like to spend a little time reckoning with where I am in life. In that, I am using reckon in the old sense: to count up. As in, count up what I have achieved in the year as fall slides toward winter, toward shorter days and longer nights, my time to be more contemplative.