Meanings of the life
Everyday level
Maximize the duration and quality of life for those you care about and for yourself.
Evolutionary level
Increase the survival chances and the quality of your offspring.
Population level
Make the biggest possible contribution. An Indian guy makes a 30-second video on YouTube showing how to fix a something. It saves someone one minute a day. Ten million people watch and use it. He has just saved more human life-time than he will ever live himself. The same, but more do doctors, teachers and scientific every day.