I'm sorry you lost motivation. It happens to all of us. It happened to me just last week because I had been steadily losing weight and was almost 10 pounds down and then due to increased salt intake I went back up a few pounds. It's hard to see the scale go up after working so hard, and hard to stay motivated and on track even when you know your weight gain isn't fat.
Some things that help me get back on track are reading motivational stories. Try the motivation resources on SparkPeople: www.sparkpeople.com/resource/motivation.as
The success stories, motivational quotes, and other resources really help me.
Also if you are a visual person like me, you can look at motivational fitness pictures on Pinterest or Tumblr. SparkPeople has a Pinterest full of lots of good resources and motivational pictures: pinterest.com/sparkpeople/pins/
You can visit my tumblr here:journey2healthyandfit.tumblr.com
And there are many more blogs and pins of fitness and motivational resources if you just search for them.
Write down reasons why being healthy is important to you and how you feel when you make healthy choices and hang it up somewhere you can see it often. And if you are getting bored of the same routine find fun new ways to exercise with your kids or new recipes to make. Change always motivates me when I get bored of doing the same routine.
I hope one of those ideas help! We all lose motivation sometimes and just have to push through and remind ourselves why living healthy is so important and worth it.