The Sheloh Hakodosh, based on words from the Zohar, defines Avraham Avinu's life in the same vein. The Torah tells us וְאַבְרָהָם זָקֵן בָּא בַּיָּמִים - and Avraham was old, advanced in days. The Sheloh explains that a day, when one performs mitzvos and maasim tovim is considered a 'day lived'. Otherwise, it can be deemed a 'dead day'. With this he explains that Avraham was זָקֵן, he reached a ripe old age, since בָּא בַּיָּמִים, all his days were 'lived'. Avraham Avinu accumulated a treasure of 'days'.
For this reason, adds the Sheloh, chachomim in the Torah are called זְקֵנִים - elders, for they live each day to its full capacity, thereby reaching their ripe 'old' age.