I know this question was posted a long time ago, but I feel like sharing what I think, or what I know about the subject. For my answer, I will use a personal experience, but I'll spare personal details...
Back when President Hinckley gave the challenge to read the Book of Mormon before the end of the year, I was just 16. I hadn't completed the book of Mormon before, and the challenge and promises that he made if we would do this simple task of reading the book cover to cover kind of excited me. So I did it. One night in particular, I was reading through 3rd Nephi, and as I was reading the account of Jesus Christ's visit to the Americas, the Holy Ghost really filled my heart with unexplainable joy. I have felt the Spirit before calming me, or letting me know something was true. Gentle, peaceful feelings. But for the first time, I felt unsurpassed joy. So... after reading, I got on my knees and prayed. I just let Heavenly Father know what I was feeling, and that I was so grateful for Jesus Christ. I prayed that I could continue to have this feeling throughout the night. And when I said amen, instead of laying down and going to sleep like I normally would, I just pondered or meditated on that feeling. I meditated on the feeling the Holy Ghost was giving me. I meditated on the story that I had read. I meditated on Jesus Christ. And then, like so many stories say in the scriptures, I was caught up in the power of the Holy Ghost, and I experienced something so sacred that I have never experienced before!
The Holy Ghost is THE MOST powerful witness of God that we can ever have. Why did Laman and Lemuel continue to deny truth and light when they had so many physical witnesses of it? They saw angels, and yet they went on in disbelief. Why? It is because they never felt that sweet, powerful witness of the Holy Ghost, which is the greatest witness. And if they did, they denied it... So I believe that meditation is a wonderful way to receive answers to prayers, and to connect our minds with the things of the Lord! We can meditate by reading our scriptures prayerfully, seeking the Holy Spirit, and pondering on the things of the Savior while the Spirit reveals to our minds what is good and true. Incredible things can happen.
And yet... as amazing as was the vision I had through meditating... it was still nowhere near as wonderful and memorable as was that joyful, wonderful feeling of the Holy Spirit testifying to my soul of the love my Savior has for me!
As for Karma... just look at the Book of Mormon! Whenever the Nephites were carried away in their pride and the vain things of the world, it didn't take long for destruction and sorrow to come upon them. Where much is given, much is required. And where we fail to recognize those great blessings which have been given to us by the mercy of God, we lose the joy and the peace that can be ours by simply loving one another, and being grateful for what we have.