My biggest excuse, and I hate to say it is my kids
I can't excerise when the kids are around, they always get in the way.
The kids just wear me out, after cooking dinner, giving baths, getting them ready for bed, and picking up once they are in bed.
I have to eat what my kids eat.
I have to cook for them every day.
Other excuses:
I'm just too tired
I can always start tomorrow....
I have a lot of errands to run.
I'm sure there are more, but can't think of them right now.