Kyle Korver has become perhaps the NBA's most lethal three-point shooter, an accomplishment that is all the more impressive considering he is 33 and has played on three teams the past five years.

Last season Korver led the league with a 47 percent mark from beyond the arc. He also recorded career highs in games started (71) and minutes-per-game (34).

How has Korver managed to defy age and time? In an excellent profile on Grantland, Zach Lowe describes Korver's ambitious offseason training regimen.

Marcus Elliott, founder of the renowned P3 Peak Performance Project in Santa Barbara, Calif., introduced Korver to the concept of misogi, a Japanese annual purification ritual. Korver explained it in an article from December 2013.

“There's a jiu-jitsu concept that was introduced to me this summer called the misogi," Korver said. "It comes from the idea that as we get older we take fewer risks, think more inside the box, get more careful, make more decisions based on fear. To combat this, once a year you do something that you’re not sure you can do. That's the misogi. I'm not talking a marathon -- lots of people do that. It’s more like, climb to the top of the farthest mountain you can see. That’s where I’m gonna go."

Last offseason, Korver and Elliott stand-up paddled 25 miles for their misogi. Then Korver had one of the most productive years of his career, even breaking the NBA's all-time record for most games with a consecutive three-pointer. He ended his streak at 127.

This offseason, Korver has already completed his challenge. He and four friends split into two teams and did a collective 5K while holding an 85-pound rock. And did we mention they did this underwater?

Lowe writes:

"Each participant would dive down, find the rock, run with it as long as he could, and drop it for the next guy to find. Those waiting their turn wore weight belts and tread in water between five and 10 feet deep."

The entire challenge took five hours, and Korver said he and his buddies were worried about blacking out and/or encountering sharks. Thankfully, they survived and Korver is currently in Las Vegas trying to earn a spot on Team USA's roster for the FIBA Basketball World Cup.