I highly believe that the most important thing is to have a proper routine. 
If you have fixed times when you exercise, eat, wake up an so on, not will it help you to preserve mental power to more important decisions, but will also help you to do all of those things rather than find an excuse to skip it.
I have been working from home for years, and the only way I can efficiently exercise and prevent overeating is sticking to my routine.
Just some ideas:
These surely helped me a lot, so maybe it will do the same for you!
If you have fixed times when you exercise, eat, wake up an so on, not will it help you to preserve mental power to more important decisions, but will also help you to do all of those things rather than find an excuse to skip it.
I have been working from home for years, and the only way I can efficiently exercise and prevent overeating is sticking to my routine.
Just some ideas:
- Know what and how much you will eat in advance (have a plan or prepare food for next day)
- Reguraly exercise (it does not even have to be very extensive, but if you stick to some activities every day, you will be amazed by the results)
- Always exercise at the same time (find what works for you and stick to it. I even have alarm clock st to go on 11.30 AM which means I am going to stop working and do some exercising)
These surely helped me a lot, so maybe it will do the same for you!