I thinks what he meant was life is short no matter how long you live. To a 20 year old, 40 is a lifetime away. To a 40 year old 20 was yesterday. Imagine being 80 and wonder were the time went and all the things you wanted to do but never had time.
The Story is pretty good. Life on Mars in the distant future. A scientist develops a plant that will bring breathable air to the planet and was killed because of it. Now he will be avenged and the air brought to the planet by this guy. Don’t have the names down yet.
Old people were probably about 30 years