What do you do when you want to have sex but hubby is always saying he is tired?

Offer to be the one "doing the work" and he can just lay back and enjoy the show? Haha but if he's exhausted, best to not force it, no one will get satisfied in the end. If it's time and exhaustion getting in the way, maybe you and hubby can "schedule" sex in e.g. on days where you guys are not working. Not the most romantic but it's practical.