One of the keys to a successful and fulfilling marriage is friendship. You were head over heels in love when you got married, but if you've noticed things have become a bit predictable, here are a few suggestions to reignite the spark and enjoy life with your spouse again.

Protect his back

Couples in the healthiest relationships act as a team. Such teamwork, marriage and family therapist Sharon Rivkin explains, "creates safety in the marriage, which then creates closeness and trust." You don't always have to agree, but your husband should always know you are on his team, even if you disagree on certain issues. And if you think he is wrong, you can still allow him the right to feel the way he feels and be supportive.

Reframe your arguments

When you're upset, it's easy to get carried away and turn a slight disagreement into a battle, especially if you feel you've done nothing wrong. But there are better ways to handle these inevitable differences of opinion.

The next time you disagree, Rivkin suggests asking yourself this question: If I this was my friend that I was upset with, how would I respond? If you look at your spouse in that light, chances are, you will approach the argument much differently.

Initiate the fun

In his book "Blueprints for a Solid Marriage," Dr. Steve Stephens highlights the strength that comes from having fun together. "Couples who know how to play and have fun together develop a bond that can carry them through the most difficult of times," he says.

"Most couples work too hard to really enjoy their life together. They feel that if they aren't doing something useful, they are wasting time," writes Dr. Steve Stephens in his book "Blueprints for a Solid Marriage."

Share a hobby

Having fun together becomes easier to do when you share common interests, and the couple that geeks out together stays together. It's one thing to enjoy a game of golf or see your favorite band in concert, but there's another level of closeness when you can learn and acquire new things, work as a team, or just indulge your nerdy side each time you engage in a shared hobby together.

Try building or refinishing furniture, cooking new cuisines, training for a marathon, learning to wakeboard, or even just exploring your love of all things "Doctor Who."

Let him be himself

Allow your husband to be who he is and like what he likes. Giving him space will show him he is respected, valued and safe. In return, he'll not only give you that same respect, but he'll also open up and be more willing to share his true self with you.

Start an offbeat tradition

When life is busy (isn't it always?), it can be hard to schedule time to get together with friends. Don't let it be your excuse with your husband. Start an unusual tradition-or two or three-you can both look forward to.

Traditions "help shape your family by creating a sense of unity, warmth and closeness," writes Tsh Oxenreider for The Art of Simple and "create memories that fill your mind with peace, love, happiness and security." Treat yourselves by creating an "impulse shopping day," celebrate the anniversary of your first date by recreating it, or kick off summer with an annual fun in the sun day, with a little help from color-changing clothing and accessories.

This article is brought to you by Del Sol. Del Sol's merchandise changes colors in the sun. The science is different for marriage, but the principle is the same - relationships can change. Let the sun shine down on your marriage as you change for the better.