As dramatic as the title is, what I am about to tell you is true. Now, first things first, we have to understand what "success" is. Success can be defined by lots of different people as lots of different things. I get that. But, overall, success in my opinion is: "accomplishing a goal/objective that you had set yourself"
The reason why people view success differently is because they have different goals/objectives. For example, someone who wants to add 10kg of muscle will see it as a success when it is done whereas someone who doesn't want to do that will look at it and think waste of time.
So what it comes down to is this.
Success is all about how you view yourself. How you treat yourself. The goals/objectives you set for yourself and how you can achieve them. I would argue that the path to being successful is more important than the success itself. Skills are learnt along the way which will prove vital in your future endevours.
REMEMBER! Set goals/objectives. Create a plan to get there. Push and push until you reach your goal.
(REPEAT for the rest of your life)