How Do You Tell Your Spouse They Physically Turn You Off?

Physical intimacy is an important bond in a marriage. But what happens when the intimate relationship dies because you find your spouse a turn-off? Whether its excessive weight gain, poor higene, or perhaps just the lack of effort to look appealing, when intimacy is missing because physical attraction has died, this can be the beginning of the end of the marriage. How do you tactfully and lovingly tell your spouse they turn you off - and help them understand what they need to do to turn you on again?