I have an app on my phone to remind me to go do something - a walk or a bikeride or something. The eating, I'm pretty good with, by having built the habit over time, a little at a time. Like, drink a glass of water before taking seconds of anything, to see if I'm still hungry. Or, use a smaller plate for the food. I used to measure or weigh everything before I served it so I knew how much I was eating. I had no idea what a portion size *looked* like. I eventually learned over time most things.
I still weigh or measure anything unfamiliar. I put whatever snack or treat I'm having in a pretty plate or bowl, and PUT THE PACKAGE AWAY before I eat any of it and then go sit down to eat it. It makes it something I savor more, and prettily presented, it satisfies the aesthetic part, like it would in a restaurant. And it triggers that "this is how much there is and there ain't no more" mechanism, by not having a whole bag of it sitting right there calling to me.