What does it mean to be balanced

Balance or a state of equilibrium can be achieved only true constant small adjustment. Think of it like Balancing a pencil on your finger just to keep pencil Still you have to make constant adjustment with your hand.

Because everything constantly changes it is impossible to remain still.

If you haven't made this realization yet, it is easy to look at these natural fluctuations and believe that something is wrong. Which is going to make the experience a lot more stressful. Being crazy is not so much about being abnormal as much as it is being normal and believing that you are abnormal. And this is going to provide an abnormal level of stress.

When you're trying to achieve balance in your life like for example between your work life and your personal life, you will occasionally become unbalanced a slide from an extreme to another. This is pretty much an unavoidable dynamic, but left unchecked it will destroy your life.

So it takes your awareness to realize that you need to make some adjustments to your life, to make sure you are not neglecting any of the important things.

But because Balance it's not so much about being still it's about constantly moving in a way that it allows you to grow and improve. It is also about virtue the way the Greek philosopher Aristotle defines it as the point between a deficiency and an excess of a trait.

It is not moderation as some people see it as doing a little bit of everything. If doing everything in a small quantity would be moderation then, this would mean that steeling from time to time or raping someone as much as you are not doing it in excess you are a healthy balanced human being. That is not moderation, is excess even if you are doing this activities in small quantities you are still indulging in excess, even if you rape only one person in your entire life you are still a rapist. You can't be to much or to little of a rapist, or to nice, or to bad. This are all extremes and from a grammar point of view don't make to much seance.

There is some confusion around this because people sometimes use things like balance or moderation to justify their vices. The person that is an alcoholic might say that he/she is just having fun and enjoying the evening, after all this is how vices are maintained you need to maintain your ignorance by justifying your bad habits. I never meet anybody who had a vice and was aware or honest about it.    
Moderation is doing enough of a certain thing until the objective is reached without hurting yourself or anybody else.