Balancing the Five Powers

It is too easy to understand, but it is very hard to done.

The example in concentration meditation:

1. If you have too much trust to concentrate on focus, you will over hurry to sit and to meditate. That hurrying maybe make you miss to concern, smart & wisdom, the meditation's situation and environment, such as it maybe too hot temperature to develop concentration meditation. So, your meditation will not grow up.
2. If you have too much effort, you will too much concern the meditation's situation and environment, then you loss the meditation's focus. So, your meditation will not grow up.
3. If you have too much concentration on focus when you still being bore, you will sleepy. But you will not decide to stand up and go to do caṅkama, walk meditate, to avoid sleepy. Because you miss to concern, smart & wisdom, the meditation's situation and environment. So, your meditation will not grow up.
4. If you have too much smart and wisdom, you will too much concern the meditation's situation and environment, then you loss the meditation's focus. So, your meditation will not grow up.

Etc.

For more information, I recommend you read whole of path of purification especially in pathavīkasiṇa-niddesa and in maggāmaggañāṇadassaṇavisuddhi-niddesa. There are many explanation and many tools for the balancing inside there, such as 7 sappāya, 10 appanākosala, etc.