Amid the gifts and Father’s Day festivities, an undercurrent of confusion can be detected. As a dad for over 30 years, I know that figuring out what constitutes “good fathering” can be something of a challenge. We live in a society of rapidly shifting roles and responsibilities, and many fathers (and mothers, of course) are looking for what makes parenting really “work.”

So what if, out of the enormous muddle of child-rearing advice, there was something close to a “magic bullet?” What if there was one course of action you could take to create life-long, loving relationships with your children, serve as an “early warning system” for problems your kids are having, and lead to positive relationships throughout life?

In our interviews with over 1,200 of the oldest Americans for the book on the Legacy Project, we asked them in detail for their advice about parenting. I think they qualify as experts, given that they have raised a total of nearly 4,000 children. In our hectic and driven society, parents look endlessly for programs, gimmicks and therapies to improve their relationships with children. But what do the elders say?

According to them, there is one key to successful parenting: Spend more time with your children. And if necessary, sacrifice to do it. The elders tell us that there is one great contribution to lifelong closeness for which there is no substitute: Your time.

In their opinion, your kids don’t want your money (or what your money buys) anywhere near as much as they want you. Specifically, they want you, with them. Parents who work double-shifts to keep the family afloat may have no choice. But if you and your spouse work 70-hour weeks to buy consumer goods and take lavish vacations, they say you are misusing your time. Even if it means doing with less, America’s elders tell you that what you will regret at their age is not spending time with your children. And it’s what your children will regret, too.

They also told me that the activity you and your kid engage in is not particularly important: It’s the shared time. In off moments during whatever the activity may be, there’s time to talk, to share confidences, to connect. And in those activities, the miracle of real communication sometimes occurs.

I remember an essay by former treasury secretary Robert Reich about his sons. He used the analogy of a clam to emphasize that to really know our children we need to be there at exactly the right moment. Our kids are often closed up tightly like clamshells, hard on the outside but with a soft and vulnerable interior. Suddenly and unexpectedly, however, they will decide to open up, and if you’re not there, Reich says, “you might as well be on the moon.”

This is why time spent together is so critically important. No scheduling of “quality time” (whatever that is) has you there at the precise moment when Matthew decides to tell you that what is really putting him in such a bad mood is the English teacher who just hates him, or when Allison will reveal that yes, there is this one boy in her Spanish class…

Clayton Greenough, 79, has very close relationships with his son and daughter, both of whom settled nearby as adults. When asked for his lessons for child-rearing, he reflected on the importance of going along with children’s interests, making them shared activities.

Maybe it’s maybe an old fashioned way of speaking, but I feel that it’s pretty important to stick with them. I know when my son was about 12 or so, he was fascinated by anything with an engine on it, even with lawn mowing. Generally I tried to go along with him. With lawn mowing, for instance, I finally said “okay, you can push it” but I stayed with him and worked with him for a while.When he was a sophomore in high school, I started putting up a shed in our back yard. And he had just gotten into a carpenter shop at high school at the time. I had him help me there, and before I knew it, I’d come home from work and he was sitting out there with a tool box waiting to go ahead with some work. And ultimately this led him down a road where he actually saw the need for measuring and things like that, and started to recognize that there is some value to arithmetic and mathematics.

And he eventually wound up being a mechanical designer. Now if I hadn’t been available to him at that time, I’m not sure what course he might have taken. So many of things that he’s doing now were initiated because we spent time together. I think the fact that there was somebody who was there and interested in what he was interested in.

Interestingly, the elders often highlighted time shared in mundane daily activities and interactions, rather than memorable “special occasions.” Their message is to involve your children routinely in your activities, and this requires your physical presence for large blocks of time.

Larry Handley, 84, described how important such experiences were for his children:

When they get old enough to kind of help you around, you know, let them help doing things or cleaning. Maybe you’re out digging in the garden or something, or whatever, to share in the chores around the house or the yard. Helping either the mother or the father, doing things that are not always that easy or pleasant, but you know, to get it done. So, these are things that you don’t realize but they do come along for their whole life, they can enjoy those things and you can too.

Time spent with children is critical for another reason: It serves as a key “early warning” system for emerging problems. Betsey Glynn, 78, has two children, a son and a daughter. She was able to head off problems in their lives because she was right there with them:

It’s so important, while your kids are growing up, to be with them and support them. Because otherwise you don’t really have a clue what their direction is, what they like and don’t like and what they want to give their time to and what they’re doing with it. This way we not only went to their games or concerts, but we met the other kids on the team or in the band or whatever it was. Otherwise they would have gone off and who knows who they would have associated with?Let me tell you, if your kids have a concert or a game, you should put aside whatever it is — if the house needs fixing up or the laundry needs doing, it’ll wait. It’s more important to devote your time to whatever they’re interested in. Otherwise you’re going to lose them. They’ll become strangers.

So to those of us getting ready to be acknowledged on Father’s Day, America’s elders bring home three key points. First, it’s your time that kids want and they will look back on the hours together with fondness and nostalgia. The elders remember this from their own families — indeed, it is the source of most of their pleasant memories about childhood. Second, what counts the most are shared activities — time spent in hobbies, sports, camping, hunting, and fishing (it’s extraordinary how many older men cherish hunting or fishing trips with their fathers), and in seeking out a new interest together. Third, the elders agree that we should be willing to sacrifice to have that kind of time. If you are going to have kids, they say, it’s worth it to live on less to be able to be with them.