Hartley, 43, tells the host that stay-at-home orders gave him incentive to work on personal development. Plans included learning an instrument, mastering a foreign language, and working out in his new home gym. But things quickly went awry while pumping iron.
"I ended up doing something really kind of ridiculous," says Hartley. "I tore my bicep off my arm. It was nasty ... the tendon that holds it to the bone apparently, I guess came off. It sounded like if someone just ripped your shirt."
Hartley explains that it was all the result of a basic bicep curl gone wrong—"I think I jerked the weight or maybe it was too much weight for me," he admits.
"I think I was in shock," he continues. "But the way I would describe it ... it felt like a grain of sand, then it turned into a pea, and then a marble, and then a golf ball, and then a tennis ball, and then a softball, and then a watermelon... and like a human head was in there. I think it was the swelling."
Hartley had surgery on the arm and later watched a video of the procedure. He tells Ellen that he saw his own tendon pulled out of him arm, to which the host simply remarks, "Disgusting."
He adds that with his right arm out of commission, he couldn't follow through on guitar lessons. He also kids that the injury threw a wrench in his plans to learn Italian, because he wouldn't be able to gesticulate while he spoke. "It messed up all of my plans," jokes Hartley.
But after taking three months to heal, Hartley says he's pretty much recovered. "I'm like 95 percent right now," he says. "It's just a little tight, but I'll be alright. I'm lifting weights again." Good thing it's back to business as usual because a torn bicep is the last thing his This is Us character, Kevin Pearson, needs on an already-full plate.
The two-hour, season 5 premiere of This Is Us airs tonight at 9 p.m. ET on NBC. You can catch the full episode of The Ellen DeGeneres Show featuring Justin Hartley today on your local network, check here for show times.