Motivation is one of the hardest things to fake. If you aren't truly motivated to get out the door and go for a run or hit up the gym, you're going to have a difficult time getting there. That's why if you can't find it deep within yourself to work out for the sole reason that it's good for you (don't worry, I can't do that either), then create motivation.
If running isn't your thing, find some other way to hold yourself accountable. Sign up for a workout class at your gym. If you've already paid for the classes, you won't want to miss them. Buy a swim suit that you want to look great in on your next vacation and hang it on your bedroom door. When you see that, you'll remember to put on those gym shorts and get active. Maybe you can't fake motivation, but you can certainly find a way to make a little of your own.