You could try to involve him in exercising together. I know when I'm in a bout of depression regular exercise helps no end (Also boosts sex drive) You could do something like go to martial arts classes etc etc. Also, things like eating good food rather than junk helps. Doesn't have to be anything fancy, grilled chicken, plenty of fresh veg etc

If that doesn't help I personally would have a go at him. You're out in the day working and bringing home the money while he sits around all day. You deserve more respect than that, even if its just that he does the housework or cooks dinner for you. If having a go at him doesn't help then I think it's probably time to take a break, because if he doesn't want to change then you can't make him and it's just going to hurt you more if you keep trying.