cmayfield I think you have a good point. I was looking around at a lot of men who are near to my age at the weekend, and most of them were carrying so much belly fat they looked pregnant. It's not a very attractive look and to be honest, I can't believe that any woman would look at them and think "wow sexy!".
You are allowed to have the feelings you have. If you don't find your husband attractive anymore are you supposed to force yourself to have sex with him? We are "programmed" to find fitness attractive - it is how we ensure our children have the optimum genes.
The problem is that no one can make your husband lose weight. Your husband needs to decide to do this himself, and for his own reasons. Maybe you could couch it in terms of trying to stay as fit and healthy as possible into old age so you can make the most of it? Of course we are all at risk of accident or illness, but getting fit and doing our best to maintain fitness at least gives us a chance to fight the odds. Cardiovascular exercise is really important to keep the brain healthy into old age.
I'm not sure that "going to the gym" is the best choice of exercise for him if he's inconsistent. If he is out of shape he may also feel insecure amongst all the gym posers. Could you find an exercise activity you both enjoy, maybe running or swimming? Or could you exercise at home - there are loads of YouTube videos, The Body Coach is a good one because it's a man who takes the piss out of himself a bit and isn't perfect.
I hope that you find a way through this and that your husband does take his physical fitness more seriously, not just because it will make him more attractive to you, but because it means you both have a better chance of being healthy and active into old age and that is the best prize ever.