Perhaps, instead of suggesting that he eat healthier and exercise to up his sex drive, why don't you be a little sneaky about it. If you do most of the cooking, start trying to cook healthier meals. If you eat out a lot, maybe suggest you stay home and cook dinner together. In regards to exercise, maybe simply suggest after work at night to go for a walk. On weekends or days when you're both off from work, try to do something active together, suggesting it as something fun the two of you can do together. Throw a frisbee around, go for bike rides, hit a tennis ball back and forth. If you do these things simply to have fun and be together, he won't feel as pressured in regards to sex, so maybe the combined healthy eating, exercise, and spending quality time together will increase his libido.