It’s as simple as deciding to act. And it doesn’t really matter what it is. When I get in a funk with programming workouts for the gym, I just start writing movements. And then reps. And eventually, awesome workouts start flowing out of me.
If you’re stuck with your eating habits, waiting for motivation may set you further back (because who knows when it will come). What you can do is decide to act. Do something. Go wash a carrot and eat it. Then you’ll think “I’m healthy as fuck right now” and maybe eat another. And then think “I bet a steak would taste great with these carrots”. And you’ll need to wash it down with some high quality H2O. And before you know it, you’re planning out your meals for the rest of the week. All because you decided to eat a carrot.
Do something. Decide to take ANY action right now.