It's can be hard. I know when I get a bit sideways I revert to grabbing a vanilla slice of cake on the way home, have a coke, sit at the computer until I go to bed. Breakfast can be a couple of donuts and a coke with lunch being a trip to Subway. And If my boss got to me during the day, which was, maybe still will be, pretty common, I won't sleep while I churn the day.
I've realized that I have to force myself to go climb a hill when that happens. It takes about an hour but the up is strenuous enough that it usually knocks the worst of it out. I also have a fitbit that reminds me to move every hour. I work in a 8x10 room with no windows so I can literally go all day and not talk to anyone. I barely see people in my own department. It forces me up and to move even if all I do is walk back and forth in the hallway for a couple of minutes.
I also have a rowing machine and 30 minutes on that helps a ton too.
The fitbit also has a guided breathing program, something I try to do every so often for the 2 minute cycle at least.
During lunch, I may still eat poorly, but I make sure that I go for a walk or get in my car and go somewhere. Even if I just sit in the car at least I'm out of the office and I'll typically nap or meditate a bit.
I won't even comment on the weight. I've been crazy fit my whole life except for occasional stints and I saw a picture of myself, and oops, not any more. The good news is that I actually looked younger than I am but damn I was fat.