In reponse to things heard and read as of late:
The ability to "live for Christ" isn't from pulling ourselves up by the bootstraps, really really meaning it this time or even by "getting right with God" or "re-committing" yourself to Him. That ability isn't in us, never was and never will be. The ability to "live for Christ" comes from Christ Alone, the one who's death even offers forgiveness for when we don't "live for Christ."
So take heart, knowing that when we try on our own, relying on our own fortitude, we will fail, for Christ has always know that this would be our outcome. That's why He succeeds for us when He works in us for His purpose. Apart from Christ we can do nothing. To live for Christ is to live because of Christ in thankfullness of the work of Christ. There is no good in us that is not of Him.
When we fail time and time again with great consistency, remember that Christ forgave even that. Rest in His arms knowing that you are His child. Stop trying in and of yourself to do good, for you will fail, and simply let Him give you His strength that He would accomplish good through you.
Soli Deo Gloria