I'm going to tell my wife I'd like her to get into better shape so that we can have a better sex life
Don't you feel your wife might take offense to you telling her to get into better shape?
I think she will, our sex life isn't very good and she's so lazy about it.
Wanting your wife to be more healthy, whether it be for your sex life or in general, is a good thing but the way you want to go about it is really rude. You shouldn't just tell someone they need to exercise more. Try asking her if she wants to work out with you and encourage her to do it that way.
Well, maybe I'll try it later, it's hard to get a woman motivated you know.
Your first mistake might be assuming that women are unmotivated. Instead of having such an attitude, try being more open minded about how you approach your wife. Try being sincere in your efforts and let her know how important your sex life is to you.