To me, being successful means...
I think success is being generally happy with what you are doing. I don't mean overjoyed happy every minute of every day but I am achieving success when I wake up ready to start the day and go to bed feeling I accomplished something and had time for those I love. I also think success is making that happen while balancing my family/friends and being there for them and enjoying my time with them as much as I can.

My definition of success has changed over time. 
Growing up I thought of success as being the most educated I could be and then working the hardest to get the highest paying job or best job title no matter what sacrifices I had to make in my own life. Honestly, I have none of the above things now (except the education piece perhaps) and I feel better about my life then ever.