The 45-year-old actor feels 'guilty' for scaring his loved ones, including wife Kristen Bell.
"I was passing six guys on Sonoma Raceway on a motorcycle and I was braking very, very hard — hard enough that the back wheel was off the ground for a good 100 yards," he explained. "And then someone turned in, as they have the right to, I was totally at blame. I thought I would be able to slide in between, but someone turned in and I was already under full brake and I couldn't go anywhere."
Shepard went on to reveal that he clipped the other rider's bumper and "went over the handlebars and landed pretty hard."
He called the moment "a little demoralizing" as it was his first time on the track and said he got yelled at by the track crew for not getting off the track soon enough after the crash.
"They really let me have it and I was too injured to object, so I just took it on the chin," he said.
After icing his injury, Shepard "went back out" but eventually left because "it was too painful."
"I've been at the hospital for seven hours today," he said. "The final tally was four broken ribs, the clavicle's broken in three places, and I need surgery. And then I broke my hand that I'd broke a couple months ago."
Speaking to his co-host, Monica Padman, he added, "I feel very bad. It's inconvenient for everyone. It scares everyone. I'm sure you and Kristen [Bell] were scared and I feel guilty about that."
But that likely won't keep Shepard from getting back on a bike.
"I don't think I'm going to quit, but I think I might be willing to quit for the remainder of 2020," he said.
Shepard later took to Instagram to show a shirtless pic of his injuries, writing, "Thank you Armcherries for all the well wishes and concern. I'm in one piece and spirits are high :) Sorry for causing concern. ♥️🍒♥️🍒♥️"
When comedian Whitney Cummings commented on his wife Kristen Bell's face in the background of the photo, The Good Place star replied, writing, "Just politely shaking my head at his nonsense..."
This isn't Shepard's first injury in quarantine. Back in May, Bell detailed how Shepard "crushed all the bones in his hand" during an off-roading trip. Watch the clip below for more.