I think what's changed this time, and got me feeling more motivated (though I'm only a week in so hoping it will keep me going) is i have a really active job. I work with kids, teaching drama, and I was coming out of hour long classes exhausted!
The final straw though was when I looked in the mirror, wearing an "oversized shirt" I bought a month earlier. It was a size too big when I bought it, and now it was gaping all over. That's when I knew that I had been way too greedy and lazy over the last few weeks.