Okay, I think, that the whole premise of your agreement... is not gonna fly.
Basically, if your/his sex life is only about a person's weight and non-circumcision... then well, I say just deal with it.
He wasn't circumcized ever since you knew him and was born that way... so why only "now" is that a problem?
Next, if your weight bothers him, well I'm sure he is no Brad Pitt either. So tell him get a grip.
A marriage/sex relationship takes all forms and effort. No all women are perfect models either... so he better get real.
It seems you both a bit sarcastically targeting each other and putting high expectations upon each other. Not realistically.
But yes, exercise for health is good. For anyone.
I personally, would not "make" a man/My Husband get circumsized.
My Hubby is not, in fact. AND... it makes no difference. It is the way he was brought up. In Europe... they are usually this way. Natural.
all the best, you will get a ton of opinions on this,
Susan