For me it is one word: Results
I am sticking to it because I get results that better my life, everything seems easier and better than before. Of course looking better and being stronger is great, but overall results are what I crave more of, a better overall quality of life. I also enjoy lifting, it still amazes me that you can transform your body by doing a simple thing such as lifting weight repetitively (although we sometimes over complicate this fact lol).
I guess it comes down to that old saying "You can live or you can LIVE", and the iron game lets me LIVE.