It all depends on the object of your meditation.
Let me get right to the heart of the matter. If you 'go silent' and 'empty your mind' in Yoga, TM, contemplative prayer, or through any other method, you will be opening up your mind to demonic forces. Often these forces disguise themselves as "Jesus." Remember, Satan is the father of lies and deception. If this is your method the object of your meditation is satanic.
This practice was brought to the West (America) nearly 50 years ago from the East, i.e., eastern religions. It was a deliberate act to introduce our young people to demonic forces through pagan religions. It has been an overwhelming success, so much so that it is blanketing "Christian" churches across America.
Meditation not centered on God's Word is often harmful. Isaiah 8:19 warns against "wizards that peep and mutter [same word as 'meditate'],' and "Why do the people imagine [same word] a vain thing? (Psalm 2:1).
If, however, you meditate strictly on God's Word, you will be obeying and worshipping your Creator.
"This book of the law shall not depart out of thy mouth; but thou shalt meditate therein day and night, that thou mayest observe to do according to all that is written therein: for then thou shalt make thy way prosperous, and then thou shalt have good success." Joshua 1:8
This verse contains the first use of the Hebrew verb for 'meditate' in the Bible and it is a command to meditate on the Scriptures. It is not 'clearing the mind' or 'picturing someone or something.' Rather, this meditation has a distinct purpose: to obey "all that is written therein."
The blessed person is the one whose "delight is in the law of the Lord; and in his law doth he meditate day and night" (Psalm 1:2). Only then will we be blessed.
Yes, by all means should meditate.
"Meditate upon these things; give thyself wholly to them; that thy profiting may appear to all" (1 Timothy 4:13, 15).