I have always been drawn to stories of the human connections that define us, and that interest has been reflected in my work both as a photojournalist and as a documentary moviemaker. When I was growing up, I planned to be a cultural anthropologist. I guess in a way I am, though armed with a camera instead of a notebook. I like photographs of landscapes as well as the next guy, but if you want Sumo wrestlers, Masai children or a Turkish masseur, I’m your man.

When I got into directing, I brought that curiosity to my work. Whether the subject was identical twins, a Jewish matchmaker or my own irascible father, I found myself captivated by the thrill of unearthing the indelible truths that exist between the lines.

The topic for a documentary must be chosen carefully, as you will likely spend years with it. You need to choose something you’re passionate about, or else you’re utterly doomed, and so is your film. Growing up in Los Angeles, health and the pursuit of youthfulness (or at least its appearance) were woven into my DNA. As a Baby Boomer, I was used to being part of the youth culture, the “Never trust anyone over 30” generation. Losing a parent and gaining a few extra wrinkles forced me to confront the issue of aging in a much more immediate way. I realized I hadn’t any idea how to cope with this guy staring back at me in the mirror. Thus began How To Live Forever.

When I began doing research for the film, I intended to put most of the focus on the science of anti-aging. The people involved in the cutting-edge research of that field are fascinating and wildly creative, and the time I spent talking with them and peering into their heads made me feel like a kid in a candy store. Their vision of the future is seductive: Molecular medicine and computer programming will render aging and death obsolete. That lifetime subscription I bought for TiVo is really going to pay off!

What I hadn’t expected was the surprising wisdom I gleaned from other sources. How could I have known that a poet/undertaker, a Pulitzer-prize winning food critic and an elder porn star would each have such valuable insight into the meaning of life? Martin Scorsese said that 90% of making a good film is in the casting. When you have 94-year-old Jack LaLanne working out and running the juicer and 101-year-old Buster Martin taking cigarette and beer breaks during the London Marathon, it’s just movie magic.

Working on a limited budget with subjects all over the world was a challenge. My previous films were mostly local, so this required a change in my methods. As a rule, I liked to pre-qualify my subjects before scheduling a shoot. This was of paramount importance before committing to such far-flung locations as Japan and Iceland. The trick was to have a short phone conversation to assess their suitability. It had to be short or the on-camera interview wouldn’t be as fresh and spontaneous. Fortunately, I had some great subjects who really added to the film’s heart. Once again, you have to get the casting right.

The one person I wasn’t eager to cast was myself. I guess I’m still philosophically attached to the notion that documentarians have no place in their own films, despite the fact that A) some of the most recognizable names in the industry appear in their films and B) I keep popping up in mine. In the end, the complexity of the topic and great variety of perspectives drove the need for a through-line. My editor and collaborator, Bob DeMaio, was indispensable in making all the disparate parts come together.

My father, in his inimitable way, said “Aging and death, huh? Tough sell there, son.” On this, and perhaps a few other points, we disagree. I consider the film to be about life and living. It’s in my nature to take a humorous approach to my work, and this project was no different. My hope is that How To Live Forever will get people thinking about life in a positive and productive way. I don’t believe it is my place to provide conclusions, but rather to ask the questions that will help viewers reach their own.

As for me, I learned that the most important characteristic my oldest subjects shared was mindfulness: Staying true to their values, being at peace in the moment and living on their own terms. These were people exquisitely at home in their own skin, who were content and engaged in the world. They taught me that I can stumble through life or choose my path purposefully. If I enjoy the life I’ve made, then it is one well lived, regardless of its length. But just in case they’re wrong, I’m holding on to the number for the cryonics facility.

Mark Wexler’s How to Live Forever, opens in New York on Friday, May 13, with a national release to follow. For further information go to www.liveforevermovie.com/.