The keys to a happy marriage

-DEAR AMY: Over the past six years in Cornell University's Legacy Project, we've collected the advice for living from more than 1,200 Americans (most age 70 or older). I thought your readers would be interested in the top five tips these "wisest Americans" have for people striving for a long and happy marriage:

1. Marry someone a lot like you: Similarity in core values in particular is the key to a happy marriage. And forget about changing someone after marriage; it just doesn't work. 2. Friendship is as important as romantic love: Heart-thumping passion has to undergo a metamorphosis in lifelong relationships. Marry someone for whom you feel deep friendship as well as love.

3. Don't keep score: Don't take the attitude that marriage must always be a 50-50 proposition; you can't get out exactly what you put in. The key to success is having both partners try to give more than they get out of the relationship.

4. Talk to each other: Marriage to the strong, silent type can be deadly to a relationship.

5. Don't just commit to your partner, commit to marriage itself: Seeing the marriage as bigger than the immediate needs of each partner helps people work together to overcome inevitable rough patches.

Karl Pillemer,

Cornell University

DEAR KARL: I am fascinated by this research, which is collected in the book "30 Lessons for Living: Tried and True Advice From the Wisest Americans" (Hudson Street Press, 2011). I was inspired by both the wisdom and the practical advice offered by people who have truly "been there." So often these elders reflected on relationships in their lives that had soured over long-forgotten slights; those people who were the happiest also seemed to have the most balanced and happiest relationships. Simple values such as being kind, forgiving people and being a good friend ranked very high as lifelong values.