An 82-year-old personal trainer explains how lifting weights helped him relieve arthritis and joint paint

• Personal trainer Harry King is 82 and said lifting weights has helped him manage arthritis pain.
• King works out five days a week doing bench presses, leg presses, and cardio on the elliptical.
• He said exercise allowed him to get back to an active lifestyle and makes everyday tasks easier.

When Harry King was in his 50s, a doctor told him the arthritis in his knees had gotten so bad, he needed to stop taking the stairs, and even limit walking whenever possible.

Now 82, King is not only walking, hiking, and working out regularly — he works at his local Planet Fitness as a personal trainer, leading others through their workouts.

"Weight training is the best thing I can do for my arthritis," he told Business Insider. "By exercising and weight training I've built up the muscles around the knee to strengthen it."

King said strength training has helped him get back to an active lifestyle. Over the years, he's earned a second-degree black belt and won two championships in karate, as well as kayaked and hiked across his home state of South Carolina.

"I realize I do more than most 82-year-olds," he said. "It's just a way of life for me. To get into it, you just have to take the first step and go to the gym."

He works out up to five days a week

King spent most of his younger years being active in sports. He started basketball in high school and kept up with it until about age 50,

It wasn't until he was diagnosed with arthritis that he slowed down and started to feel out of shape. But being sedentary worsened his aches and pains and started to limit what he could do. King said he knew it was time for a change when he had an opportunity to hike the Matterhorn in the Alps, but wasn't physically ready.

"I vowed to let that never happen again, to let being out of shape stop me from doing things," he said.

King found a new doctor who could help him get back to physical activity, and found going to the gym helped him feel stronger and more capable in everyday life.

When King saw an opening for a personal trainer a few years ago, he applied, hoping to pass on his enthusiasm for strength training to help other people get stronger and live longer.

He said his approach isn't necessary about seeking out intense challenges (although he'll take them, when the opportunity arises), but making sure he can keep moving.

"I don't need to push through pain to be at the level I want to be. I just want to be fit enough to do something everyday," he said.

His workouts include bench presses, leg presses, and low-impact cardio

King said his exercise routine aims to include heart-healthy cardio as well as strength training for both upper and lower body.

For cardio, King prefers the elliptical or a bike for a low-impact workout that's easier on the joints.

"I used to run a lot but my feet can't take the pounding anymore," he said.

His weightlifting workouts include lower body movements like leg presses or modified squats to protect his knees, and upper body exercises like lat pull-downs and bench presses.

King isn't lifting light weight, either. While he doesn't try to max out his weight, a typical session might involve three sets of 12 reps. On the bench press, he could be hitting as much as 140 pounds.

The goal is progressive overload, gradually increasing the challenge to continue building muscle and strength while preventing injury.

"I don't try to lift as heavy a weight as I used to, just as heavy as I need to improve my strength," he said.