I'm glad that you're eating better. When trying to gain weight, I've learned, there's a fine line between nutrition and weight.
A lot of the important fruits and veges, for example, are super low in calories...strawberries, blueberries, asparagus. We need to eat them for health, but they do nothing to promote weight gain on their own.
As for Charlie, and exercise...
I think that most of us have the same problem. Our dogs mess with us without mercy when we get on the floor to exercise. A couple of people have brought it up in the past.
The solution is always the same...to be in another room, such as close them in another room, or close yourself into a room with a door. Barring that, or crating, I don't know of a solution. I can tell that Krypto is going to be the same.
Ds says that he has a problem with Thyri. When he lies on his back on the floor...such as when his back hurts, she tries to pull him up, and won't stop. That's a new one!
I know that dogs who aren't used to being separated in another room don't take it well, but could you not let Charlie in the bedroom, and work out in there, or put him in there while you work out? I'm not hopeful about those, but thought I'd ask anyway, just in case.