To me, being successful means...
Being emotionally and physically stable while pursuing something you are passionate about.

My definition of success has changed over time. 
In high school I compared myself to my "successful" older siblings who took more AP courses than me while also having friends than me. I didn't know how to define myself outside of the standards others had set for me and was very lost. I tried really hard in everything I did but never felt it was enough. I had a terrible eating disorder which almost took my life and my anxiety was through the roof.