It's not something you think about doing, it's something you do, just the way you get out of bed every morning. You live by it. Some days are healthier and more active than others, you just keep going. There will come a time, maybe you are already there, where you don't even think twice about spending part of your day in workout clothes. It just comes naturally.
Some people live it.
There day is actually spent in gym clothes. They have to think to put on a pair of jeans over a pair of sweats. Your eating habits change. Those fries that you once craved and ate, became the fries that you craved and didn't eat, which eventually become the fries you don't even want. It's not that you have to tell yourself you don't want them, you actually don't want them.