The two things you are telling her is good, but I'd add one more. Tell her WHY you are doing this. You need to articulate that you are doing this for a number of reasons, including that you NEED a better sex life and that your marriage will be stronger due to a better sex life. It will help your self-esteem, you confidence, your love for her and your overall views on life. You know why you want to improve the sex life, so explain it to her in as many ways as you can. Odds are she doesn't understand that for you (and most men) sex in a marriage isn't just about an orgasm, but is about a lot of emotional needs being met. It's like going through a marriage without her getting a hug from you, or only if you complain about having to give it first. Make her see why you want to focus so much time on this and why it is a need.