I've started working out in the morning before work. I know everyone can't do that, but it really works for me. Then if I don't get any more exercise the rest of the day there is no guilt.
This time, for me, it's about the lifestyle change. I know it sounds boring, but something has clicked in my head. The weight loss is definitely something I want, but the exercise and eating healthy are really more important to me because I don't want to have to think about my weight again.