How do you find a healthy balance?

Between say for example:

Eating too much and not enough?
Too much exercise and not enough?
Outgoing to the point of obnoxiousness and shy to the point of a loner?
Talking too much and not enough?
Sharing things with your partner and keeping things to yourself?
Going with the flow/ moving on and allowing yourself to be upset/hurt?
Time with friends and time with family?
Time studying and free time?
Time for yourself and time for others?

Is there some kind of formula that could help you work these things out?
Is it just that life is hard and you have to decide for yourself?
If you manage it, how? How do you do it?
If you don’t manage to balance things, do you want to? Does it make you upset when you can’t?
What do you do about it?