How to tell your wife or husband...

WRONG! If you don't have some other issues, then your whole talk will look like a weight loss ploy. You need OTHER topics and Good Ol' Crash is here to give them to you. 

Your other topics are going to be: (pick some or make some up that are NON-CONFRONTATIONAL) You may want to use these first to practice and learn to gauge her response before bringing up the fitness and lifestyle issue. In fact, I recommend it. You will be able to gauge the pushback and their receptiveness. 

1) As you probably could guess, I'm in love with you. I'd like us to date again. Just because we're married doesn't mean we can't still show we're madly in love with each other. I was thinking we could have date nights. It's cheesy I know... but I was thinking we could set aside time for just us to be together and go and do new things. 
2) I think we're spending too much time in the house on weekends. We live in (______) and there are so many things we could do... there are concerts, museums, plays! I feel like we're missing out on everything life has to offer. 
3) (IF APPROPRIATE) I feel like lately you've been depressed and I'm worried about you. I'd like to help you find some of that inner happiness that used to shine so brightly. Ask if they feel depressed and if so, how can you help. Tell them that you love them and don't want to be shut out. If they are depressed then this is the first step to getting them help. Depression may be situational, chemical or even genetic. Either way, identifying it will help improve your relationship. If they are simply mad at you because they are unhappy with the relationship, does not mean they are depressed. 
4) I'd like us to look at saving for our future. You're never too young or old to look into that. 
5) Where do you want us to be in 5 years? When she asks you the same question say "Taking surfing lessons in Hawaii!" or "I'd like us to be 5 times stronger than we are today." 

PARTING THOUGHT: 

"Telling your Spouse, the Soft Way." 

I don't proclaim to have all the answers. I've dealt with several different personality types over the years. This may not apply to people who are in a severe situation. I'll post another approach for those later. It takes hours to put together a post like this. 

I know from experience that positive reinforcement is a very powerful tool. You get ONE shot at making a first approach. Many of the people on the board are looking for a way to bring it up for the first time. This was written to help you address that particular need. 

If this approach fails, then you can read some of my more hard-line tactics. But I always recommend the soft approach first. One that focuses on the positive and helps people takes ownership of an idea. 

I also recognize that this may open a can of worms. But relationships don't happen in a vacuum. You are asking for a positive change to address YOUR NEEDS. You have to be willing to address some of theirs. Everyone can improve. 

Further, I recognize that this is mostly given with a MALE TO FEMALE interaction slant. It doesn't make it any less valid. You can use this on males as well. It should about the same. 

Never forget that preparation and clarity of thought are essential. Don't go in half cocked or thinking you can "wing it" it won't end well. 

You also have to make success possible. Banning junk food isn't enough. You have to make healthy alternative available all the time... if they can have an apple, a protein bar or some healthy snack... then they are less likely to fail. 

And lastly... you fell in love with them for a reason. If all this seems too much to go through for them... don't do it for them. Do it for the ghost of the person you fell in love with. You should do it, to resurrect that person back from the dead and make them a lasting part of your life.