What a personal and universal question you have asked. In "New Life, No Instructions," Caldwell talks about change being like trying to turn an ocean liner and using a "fork as a fulcrum." She goes on to say, "Real change, though, is forgiving enough to take a little failure, strong enough to take despair in small doses."
I love that because it reminds us that change is a bumpy path and we will survive it, even thrive.
Most of us don't change until the pain of not changing is greater than the pain and fear of change. We are vulnerable when we are changing. Who wants to feel vulnerable?
You don't say what it is you want to change, but my advice is:
1. Be sure you are intrinsically motivated and invested for your own reasons.
2. Take baby steps; do a small thing differently that you are able to maintain (e.g., the plan when people go to AA is not to drink today; not "never drink again.") You can walk for five minutes, not an hour. You can tell your husband one small thing you want, say briefly how you feel about it, and ask how he sees it.
3. Put it in your calendar.
4. Ask your husband to praise your efforts; it's easy to grind down green shoots.
5. Please understand that making healthy change does not necessarily feel right, normal, or good. What we normally do is what feels normal. So be prepared to feel off-kilter. Hopefully you have a good girlfriend to support you in this change in addition to your husband.
6. Know that whoever is the one to change is making the family system mobile tilt, and while it is seeking balance again, you are likely to be the one blamed for causing change and upheaval.
7. Have good self-talk about your change. Say realistic and constructive things to yourself. Try a phrase such as, "I am doing this for my own health and well-being." Stay away from, "This is so hard/embarrassing/annoying, I don't even know why I am bothering. Nothing ever changes," as that will make it harder for you. Reminds me of Eeyore.
8. Depending on what your desired change is, find a 'buddy' to do it with. If you don't already have one for this topic, look at Meetup; there are likely others doing what you're doing.
9. Remember there may be multiple paths to the same change. Be flexible about trying experiments to find what works for you.
10. Keep it going for 21 days; that's how long habits take to set in.
11. If you're still struggling after 21 days, seek peer or professional support.
BTW, good for you for taking your life by the horns and guiding; let go of the outcome, though, as we never know exactly how it will turn out.
Let me know how you're doing.