9. Step Outside Your Comfort Zone
You have heard it time and time again (and might have experienced it yourself): "I haven't tried XYZ because it's  outside of my comfort zone." But if you feel like your relationship is stalling, or like you're comfortable, complacent, and just a little bit bored after being together for so many years, then it's time to branch out into things you never thought to try before. There's no other way that your relationship will change.

Go buy tickets to a musical, take classes together, give yourself permission to splurge on a dinner downtown once a month, buy hiking boots and see if the two of you like climbing — try something that neither of you have really done before, and make it a habit to keep pushing yourselves outside of your comfort zones. It's the easiest way to break out of a rut.