GILLETTE, Wyo. — Leigh Lassle doesn't know what he's chasing.
He's spoken to a number of groups, large and small, during the past eight years, giving motivational speeches and offering words of encouragement. He's a people person.
Throughout those talks, his audiences have asked him questions: What does he like most about what he does? What drives him to be better? What motivates him to finish what he started?
He has answers to those questions:
"My passion is people-driven. I do what I can do to make a difference."
"What takes me back every time is the fear. That's what keeps you on track."
"I have a really particular behavior. If I set out to do something, nothing is going to stop me. I'll stick it out to the end."
But what is he chasing?
Standing at the foot of the Durrance route at Devils Tower National Monument with the sun rising behind him on a recent Friday morning and minutes before summiting the Tower for the 100th month in a row, he was stumped.
"No one's ever asked me that before," he said. "I don't have a good answer for that one."
Maybe that's what makes his journey all the more special.
Lassle's story has been told before in the Gillette News Record.
At about this time nine years ago, he was diagnosed out of the blue with thyroid cancer.
"Off the couch," he said about his attitude in dealing with the disease.
Lassle had always been a bit of a daredevil. He rode dirt bikes when he was young and rarely tuned down a good time.
But there was one thing that until then he could never get over.
"I was so afraid of heights," he said. "Couldn't do it."
After his thyroid surgery, Lassle gained a few extra pounds due to the medication he was on and struggled to get back into the swing of everyday life. That was when his wife, Rose, suggested he meet with Frank Sanders, a local legendary rock climber.
Lassle had never climbed a rock in his life. He was afraid, intimidated and unsure of himself.
The diagnosis prompted him to change that.
"That was a wake-up call to reality," Lassle said. "That's when I realized not only is there more to life, but whatever you put into life is what you'll get out of it."
Lassle's first climb more than eight years ago is still his most memorable.
"Hands down that is the ultimate climb," he said. "It was all about the fight. Getting up there will change everything about you."
After falling in love with Devils Tower, the climbing community and the thrill of the sport, Lassle joined Sanders' team and became a climbing guide.
Eight years later, Lassle has also accomplished something no person ever has at Devils Tower.
He's climbed the tower at least once for 100 straight months.
Friday's climb up Durrance in 30-degree weather in early January was climb No. 100.
Although he's done it at least once each of those months, Lassle has no idea how many times he has climbed the tower overall. He has conquered all 12 of the official routes.
"Once you get it, it's yours," he said about the lure of climbing Devils Tower. "It sucks you in."
Lassle started out wanting to climb the tower every month for one year. Once a buddy of his dropped out of the consecutive streak, he picked up the slack and kept it going.
It was never his intention to make a run of 100 straight months. His goals were always changing and as the years went by, Lassle said he couldn't think of a reason to stop.
Last winter was when he came the closest to interrupting the streak.
The climbs in December 2017 and January 2018 were the most difficult he has endured in the last eight years.
"The weather was so challenging that it got to a point where it was borderline insanity ... in those conditions," he said. "It made me think about the whole challenge last year."
Then again, here he was in January at the Tower, kicking away snow with his climbing shoes from the base of Durrance while the wind whipped around the southeast corner of the rock.
Although Lassle doesn't know what he's chasing specifically, he knows the why carries over month after month.
It's because he's still scared.
"Everybody in the world, their setbacks are fear-based," he said. "I think if you can overcome the fear and know you can get through it, then you can move forward and accomplish even more difficult, harder tasks. The fear pushes you."
At 49, Lassle is the most active he's ever been in his life.
He hosts a martial arts course every weekday at his house, rides motocross competitively and guides climbs up Devils Tower every weekend during the open season.
In a lot of ways, climbing saved Lassle's life.
His world went off the rails after his cancer diagnosis and now he has something full of life to be obsessed with.
He has something that pushes, inspires and helps him inspire other people in the process.
Now that he has made it to 100, many will ask what's next, to which he answers: "Now I'm looking at 200."