How do we measure success?

Fantastic Question! I opine there is no thumb rule to measure success as such.
Each individual has to define his/her own definition and measurement of success.
However, I can profoundly say we have to assess regularly where we were and where we are to succeed in any sphere in which we work or we live.
Hope you understand the hairline difference between measurement & assessment - It is the Objectivity & Subjectivity respectively.