A very interesting question that most of the time you think you know its true answer… but you don't :)
I spent some time to answer this for myself since it is always relative and here is a couple of points that I consider myself successful whenever I achieve them.
1. Be loving and be loved.
2. Stay as healthy and as active as possible.
3. Bring happiness to yourself and those around you.
4. Have the luxury of deciding where you want your time to be spent.
That has changed over time but currently its about making a positive impact in the world where I'm most equipped to do so, working hard and feeling fulfilled, finding time to pursue creative passions and ensuring the people who matter to me get quality time with me regularly.
@unrealartemg yes exactly. I think I also am aware how much of that time management responsibility falls on me. I try to create healthy boundaries with work. i do over time when I need it to hit my goals but I try to not make it a daily habit that eats into exercise time, reading time, etc :)