A longevity and sports medicine doctor who completed 15 Ironmans shares his workout routine. It includes a run-commute.

• Dr. Jordan Metzl is a sports medicine doctor practicing in New York City.
• He said regular exercise is one of the most important parts of longevity.
• He strength trains in the morning and runs home after work.

From a very young age, Dr. Jordan Metzl knew that playing sports energized and helped him focus. It wasn't until years into his career as a sports medicine doctor that he began prescribing exercise to others.

"It's the most ubiquitous, effective, totally no-side-effects drug in the world," Metzl, who recently published "Push: Unlock the Science of Fitness Motivation to Embrace Health and Longevity," told Business Insider.

Exercise is also something Metzl feels is sometimes overlooked in the longevity space, in favor of fancier products.

"A lot of this stuff we talk about with longevity is not validated, like full-body MRIs and these supplement stacks," he said, noting that even the protein craze has gone too far. "I feel like the next move is going to be protein toothpaste."

Instead, he hopes people focus more on the basics of longevity: exercise, diet, socializing, and good sleep. To foster a greater sense of community, he developed the IronStrength program, a workout for runners and triathletes. He also leads its workouts, teaching dozens of IronStrength group classes a year. "It's just epic, and it's so much fun," he said.

He also tries to lead by example. In the past, he's finished over dozens of endurance events, including marathons, half-marathons, and 15 Ironman Triathlons. "I've been very much into pushing myself and keeping myself going," he said.

Metzl shared what he does in a week to stay fit and feel his best.

He takes his dumbbells to the park

Metzl starts his day around 5:30 a.m., with a 30 to 45-minute HIIT or strength workout.

One of his favorite movements is hill sprints combined with sets of 10 plyometric jump squats (a more explosive version of the movement).

"I have some dumbbells, I'll go to the park next door," he said. "I'm like this crazy guy, 6 in the morning, doing some strength training in the park with the sun coming up, but I find it really helpful."

He runs home from work — and adds extra miles

After his morning workout, Metzl usually walks about a mile and a half to his office, bringing a small backpack and a change of running clothes.

If he doesn't have anything planned after work, he runs home, deliberately lengthening his route. "I'll run up through Central Park and come back," he said. "So I do 4 or 5 miles on the way home or something like that."

A post-workout helps him feel more energized. "If I go home, I'm dead," he said. "So I try and do two smaller things a day."

Weekends are for 2-hour training runs and recovery swims

Metzl saves Saturdays for more intensive workout sessions, such as a longer run or bike ride, depending on what he's training for.

"This time of year, I'll do an hour-and-a-half, two-hour run," he said, adding that the runs are just as important for his mental training as they are for his body. "You need to be comfortable being uncomfortable, so those longer runs are a great time to start getting better at those kinds of things."

Metzl likes to work out on Sundays, too.

"I'll try and do something like a swim," he said, keeping it at a lower intensity. It makes him feel better than if he fully abstained from movement for the day.

"I don't really believe in rest days; I feel like our bodies are built to move," Metzl said. "If I have a day where I don't move, my body's like, 'Dude, what's up?' It really doesn't like it."