In June 2016, 60-year-old Marshall Reeves mounted his bike in Santa Monica, California, and began the Race Across America, a grueling 3,000-mile journey that runs from coast-to-coast.

(Bryan Cereijo)

The goal was to cross the finish line in Annapolis, Maryland, in just shy of two weeks. This goal had evaded him twice already: In 2011 he made it to Manchester, Ohio, and in 2014, he was forced to stop at West Union, West Virginia.

But for his third attempt, Reeves, an airline pilot and co-owner of a bike shop in Florida, had a new source of motivation: This year, he was racing with 3,000 Miles to a Cure, which raises money for brain cancer research.

"[The Race Across America] is about the dumbest thing to ever try, let alone three times," Reeves said before embarking on his latest attempt. "In a lot of ways, it relates directly to our fight against cancer. It's never easy, often frustrating, but the only way to really fail is to give up. So in RAAM, as in the cancer fight, we haven't failed, we just haven't won yet."

The climb up Wolf Creek Pass, in the San Juan Mountains of Colorado, is 10,857 vertical feet. | (Bryan Cereijo)

The Race Across America, now in its 36th year, is one of the longest running and highly respected ultra-endurance events in the country. But it's also one of the most difficult. With 12 states to cross and 175,000 vertical feet to climb, only about half the competitors that attempt the race are able to finish. This is why it's nicknamed the "world's toughest bike race."

Unlike other long-distance bike races that are done in timed stages, the Race Across America is continuous — once the clock starts in Santa Monica, it doesn't stop until Maryland. Relay teams have nine days to finish, and solo competitors have to finish in 12. To stay on track, racers have to meet strict time cutoffs along the way.

(Bryan Cereijo)

Reeves passes through Monument Valley, Arizona, making his way to Utah. | (Bryan Cereijo)

Racers are typically followed in cars by a small crew. Last year, Bryan Cereijo, a photojournalism student at Syracuse University, tagged along with Reeves' six-person team, capturing the journey nearly every step of the way.

It's the crew's job to keep the racer not only physically healthy and satiated, but also mentally motivated. Which means breaks are often spent massaging the truth as well as the body.

"It's a mental game," Cereijo said. "So sometimes [the crew would] have to lie to him and say the cutoff was in two hours but it would actually be in six, stuff like that to get him going."

Reeves was plagued by cramps during the desert stretch. Crew member Jacob Bouchard give Reeves a quick massage in the RV during a break. | (Bryan Cereijo)

Reeves eats KFC while he has his back rubbed. | (Bryan Cereijo)

Reeves' crew chief holds his bike as he gets ready to finish Kansas. | (Bryan Cereijo)

In the early days of the race, when Reeves had time to stop at a hotel, he would be treated to a full-body massage and a good night's sleep in a comfy bed. But after day three, rest was a luxury Reeves couldn't afford as he raced to make the time cutoffs, biking for more than 20 hours a day.

"Toward the end, they didn't think he was going to make it," Cereijo said. "He had to make a time cutoff the next day and he was just knocked out on the pavement."

The crew, including Reeves' son, Jesse (standing) massage Reeves while he eats before a full night of riding to make the Mississippi River cutoff. | (Bryan Cereijo)

Reeves passes the Mississippi River bridge, completing two-thirds of the race. | (Bryan Cereijo)

While the cooler temperatures of night rides can help Reeves gain mileage, staying awake can be tough. On breaks, Reeves would drink Red Bull and use a caffeine spray. | (Bryan Cereijo)

After crossing the two points where his previous attempts had ended, Reeves entered new, unknown territory. With fewer than 50 miles to go, he suffered bouts of disorientation that concerned his crew. With just 25 miles left, Reeves struggled to stay awake, catching quick naps in the van. But, in the end, he crossed the finish line with a time of 12 days, 13 hours, and 52 minutes.

To Cereijo, Reeves was quite simply, a "badass."

Toward the end, riding through cattle feed lots, Reeves was still able to crack a joke: "I got real beef with this wind." | (Bryan Cereijo)

This year, Reeves will take off across America again, but this time, he'll be working the other side of the race. Some of his road crew members, bikers themselves, will be participating as a four-person relay team, and Reeves will join them as road chief, returning the favor for his crew's hard work.

The Race Across America begins June 13 for solo racers and June 17 for teams. You can follow along with the 3,000 Miles to a Cure racers here.