Every married couple's Kryptonite is different. Some couples have no financial problems, but strain to maintain a healthy work/life balance. Some couples will happily serve the poorest of the poor in a soup kitchen, but have trouble inhabiting the same room with their in-laws. That's why the Vatican has recommended no less than 12 topics to be covered in pre-Cana marriage preparation programs. Unfortunately, a lot of programs leave crucial information out.

So, to make up for what went missing, my husband and I wrote a Catholic marriage advice book covering all 12 topics, from finances and work to community service and relationships with in-laws, plus everything in between. The book is called The Four Keys to Everlasting Love: How Your Catholic Marriage Can Bring You Joy for a Lifetime. Below you'll find some of our best hints from the book, arranged by topic, plus links to free downloadable worksheets.

Marriage is quite an adventure, and somehow never exactly what we expect. Our God, after all, is a God of surprises, as Pope Francis is fond of saying. The first bump in the road that many couples encounter is overcoming personality differences. Opposites really do attract, and that adds to the excitement but can also create conflict.

Hint #1: Overcome your differences by searching for and finding common ground, and relying on God who loves you both equally. Help: Download Chapter 1 worksheet.

Nowadays, fewer Catholics are choosing to get married in the Church than at any other time in recent history. Many people don’t realize what a wonderful treasure Catholic marriage is! The graces of the sacraments -- especially Holy Matrimony, the Eucharist, and confession -- are a powerful aid to couples in their everyday struggles and in times of great crisis. And the saints, our cheering section in the next life, are willing and eager to help husbands and wives get each other to heaven.

Hint #2: Seek help from the Church on earth and in heaven. Help: Download Chapter 2 worksheet.

Marriage is more than the union of just two people. It’s also a union of two families. Many couples struggle with learning to love their in-laws. It helps to remember that in most cases what the in-laws really want is for your marriage to be successful, long-lasting, and happy. By loving our in-laws and extended family members, we follow Jesus’ command to love our neighbors as ourselves.

Hint #3: Listen respectfully to your in-laws' advice, even if you don't ultimately follow it. Help: Download Chapter 3 worksheet.

Whether we work at home or in an office, nobody wants to feel like a gerbil on a wheel. Work is meant to be more than that, and deep inside we all know it. A lot of effort can be poured into finding a “dream” job or career, and that’s certainly a worthy goal. But sometimes we’re called to bloom where we’re planted and to recognize that all work has value in the eyes of God.  Realizing the supernatural worth of our work will help us to prioritize well: first, God; then, family; and last, work.

Hint #4: Do all your work with love and care because God is your ultimate "boss." Help: Download Chapter 4 worksheet.

Marital finances are a hot-button issue for many couples. But frequently couples are fighting over who’s in control and who gets to make the decisions as much as they’re fighting over the money itself. It helps for them to commit fully to the idea that what’s mine is yours and what’s yours is mine. It helps even more for them to realize that everything that is theirs has been given to them by our loving God. We are not so much owners as we are stewards, caretakers of God’s blessings.

Hint #5: When it comes to money, be "we-centered" rather than "me-centered." Help: Download Chapter 5 worksheet.

Jesus wants us to feel a special love for the poorest and most vulnerable among us. That’s one reason why programs for the Sacrament of Confirmation stress community service so heavily. But community service doesn’t have to be relegated to the teenage years. Families can reach out to meet their neighbors’ physical and spiritual needs in ways that amount to priceless gifts.

Hint #6: Help out your neighbors in small, meaningful ways by hosting a play date or buying an extra gallon of milk for them on your grocery run. Help: Download Chapter 6 worksheet.

One of the most misunderstood areas of Catholic teaching is sexuality. Many people are shocked to learn that the Catechism calls married sexuality “a source of joy and pleasure” and “a sign and pledge of spiritual communion” (CCC 2360-62). Catholicism regards sexuality as a precious gift from God, enriching marriages on a physical, emotional, and spiritual level.

Hint #7: Communicate (often!) about sex in a positive and intimate way. Help: Download Chapter 7 worksheet.

Women especially are taught to fear their fertility during their teen years when adults (with the best of intentions) warn of the dangers of getting pregnant through premarital sex. Many married couples hold onto that fear, worrying about the impact of children on finances or career plans. NFP encourages the mindset that fertility is a great blessing. It helps couples to avoid or achieve pregnancy in an effective, safe, ethical, and relatively inexpensive way.

Hint #8: Gain a greater appreciation for your fertility through Natural Family Planning. Help: Download Chapter 8 worksheet.

No matter how big our hearts are at the start, they can always grow bigger. Many special family circumstances challenge parents to do more than they think they ever possibly could. Challenges like big families, special-needs children, adopting, fostering, and stepparenting can all be transformed into channels of God's all-powerful grace.

Hint #9: Ask yourselves how far you can open your hearts to new challenges. Help: Download Chapter 9 worksheet.

There is no greater responsibility than parenting well. Our children are God's gifts to us, and they will shape the world of the future. We are called to nurture our children's bodies, minds, and souls, forming them in Christ. "If we are like pencils in the hands of God, as Mother Teresa said, then each of our children is a sketch destined to become a masterpiece," we wrote in The Four Keys to Everlasting Love.

Hint #10: Parent with heavenly purpose. Help: Download Chapter 10 worksheet.

In the day-to-day grind of life, it can be easy to forget that what we do now has consequences for eternity. This is especially true in the hustle and bustle of family life. Through the eyes of faith, we can see that our families are "domestic churches," where we share God's divine love with each other and strengthen each other's faith. A rich family prayer life can bring great peace to our homes.

Hint #11: Grow closer together and closer to God through a deeper shared prayer life.  Help: Download Chapter 11 worksheet.

The Holy Family is the best role model that any family could possibly ask for. Our Blessed Mother Mary is a shining example of grace under pressure, faith in the face of uncertainty, and perseverance through the hardest of life's challenges. St. Joseph is a pre-eminent father figure, protective, strong, and willing to share all with no expectation of return.

Hint #12: Don't just ask yourselves, "What would Jesus do," or WWJD? Ask "What would the Holy Family do," or WWHFD? Help: Download Chapter 12 worksheet.