The mind is restless and hard to master; but by constant practice and detachment it can be mastered in the end.
~Bhagavad Gita 6:35
This scripture from the east was written about two thousand years ago and even then the sages who wrote it understood that we all have trouble overcoming our busy mind when we try to master it through meditation. Their instruction is the same instruction we give today, because it is the guidance that works. This scripture gives us great promise. We can master the mind through our regular practice and also with detachment, detachment from the expectation that our meditation practice should go in a certain way, allowing and trusting that whatever comes or doesn't come that day is useful. Be persistant, it works.