The true goal of life is to get back to the source from which we came. Just as the river flow restlessly till they join the ocean, the ultimate source from which they got their supply of water, just as fire leaps and burns furiously till it merges in its own origin, so too, we should be restless here till we obtain His grace and become one with him.
If you want to be a devotee of the Lord, you must also realize the evils of undivine life. This will surely save you. Repetition of the Lord's Names will purify the mind. But along with these you must also practice vichara. When the mind entertains unholy thoughts, remember the consequences, viz. pain, disease and death. Also think of the advantages of leading a pure life. Remember the lives of saints and draw inspiration from them.