Do you attend SMART meetings? I personally believe face-to-face support and discussion is very helpful, if not essential. In addition, just doing a few exercises wouldn't be enough for me to stay sober. SMART is intended to be process with many different exercises that should be worked.
My advice is simple: don't give up, attend SMART meetings at least once a week, and if you don't have the workbook, buy it and work your way through it.
If there are no face to face meetings in your geographical area, you can utilize the online meetings at the SMART website.
But as I said, whatever you do, don't give up on yourself. You can do this.