How can I encourage my spouse to exercise without upsetting her?

[guitaaron]

I want to encourage my wife to exercise more without sounding critical or making her feel bad about her weight. She has been struggling with weight gain over the last several years and she is really self-conscious about it. I've tried to help in every way I can think of, for example going on diets with her and telling her she's beautiful as often as I can. She keeps gaining though and I think it's because she HATES exercise. Making matters worse, I work out nearly every day and I'm a distance runner, and lately she's been telling me I'm making her feel like a lazy slug. I'm trying to be supportive but I know that as long as she will not exercise the weight gain will continue, and so will this cycle of self-consciousness and agonizing over the weight gain. This has started to have a bad effect in the bedroom -- she won't undress with the lights on, lovemaking has become mechanical and boring, and it's really starting to depress me. I'm finding myself spending more and more time on work trips away from home. What can I do to reverse this cycle?