Meditation

Meditation is the practice of thinking deeply in silence especially for religious reasons or in order to make your mind clear.
Meditation is the act of reaching deep, trying to get something new, interpreting and understanding a thing well with the hope of applying the results somewhere, somehow or someday.
It's the act of chewing the word of God, our spiritual food or milk  (1Peter 2:2). So the act of chewing and regurgitating is meditation. It's necessary for it releases the power in the word.

What should we meditate on ??

1 The word of God. Joshua 1:8- This book of the law shall not depart out of thy mouth; but thou shall meditate there in day and night, that thou mayest observe to do according to all that is written there in; for thou shall make thy way prosperous and thou shall have good success. 

After meditating on it, the action that proceeds will always lead to prosperity. After meditation, there is an action. 

2 Phillipians 4:8- Finally brethren ;whosoever things are true  ,whosoever things are honest, whatsoever things are just, whatsoever things are pure, whatsoever things are lovely, whatsoever things are of good report, if there be any virtue, if there be any praise, think on these things. ...... (meditate on these)