Difficulty: Moderately Challenging
Step1
Look at yourself.
If you are not hot, don't expect her to be hot. Set an example by staying fit, eating well, dressing well, and taking care of your grooming. Don't even bother your wife until you are doing these things.
Step2
Find out what motivates her.
If you're married to the woman, you should know a bit about her personality. Does she follow the crowd? Is she competive? Does she like social, group activities?
Step3
Push the right buttons.
Once you know what motivates her, get her active by pushing the right buttons. If she's competitive, find a weight loss competition to enter. If she's social, see if she'd like to sign up for group aerobics, yoga or club volleyball. If she's into trends, start laying women's fitness magazines where she will see them (bathroom) so she will see that being fit is in and she should be fit too.
Step4
Don't be critical.
Now is not the time to tell her she's fat and if she gets any worse you're going to flip. Make suggestions and support her when she goes to the gym, or dresses up.
Step5
Be prepared to pay.
Over the years your wife may have found better things to spend money on than getting her hair and nails done. Get her off in the right direction by offering to treat her to get her hair colored or buy some nice jewlrey for a holiday. Valentine's day, Mother's day, Christmas, Birthdays - it doesn't matter.
Step6
Notice her progress.
If she's been walking everyday or making an effort to dress better for you. Take notice and let her know how great she's doing. Even if she hasn't dropped pants sizes yet, appreciating her effort will make her happy and want to work harder.
Step7
Be a team.
Bring her with you to the gym, or sign up together for rec softball. Go on long walks together at night, or take up bicycling together. When you're a team you not only support her in looking and feeling better, but you strengthen your marraige as well.
Authority 
