To me, being successful means...
Being true to your values. People are much more important than possessions.

My definition of success has changed over time. 
I went through a dark period where the acquisition of money and material possessions was most important. In the process, I lost my soul - my spirit. With material things, enough is never enough. I looked inward and realized that my values were being compromised and I was truly unhappy. I returned my focus to an appreciation for people and the earth - I enjoy my days now.