The actor, 33, appeared on The Drew Barrymore Show on Jan. 17, when he revealed one thing he loves "that no one else gets."
"I will walk everywhere," The Brutalist star explained. "And it doesn't matter on the weather, it doesn't matter if it's muddy, it doesn't matter if it's snowing, it doesn't matter if it's raining."
"Actually, that probably annoys my friends. They're like, 'What? Why? Let's just take a cab, let's take the tube, let's take the bus,' " he continued.
"If it's like a 20-minute journey or an hour-and-a-half walk, I'm walking," Alwyn further explained to Barrymore, 49. "I'm walking everywhere."
Reassuring Alwyn that walking everywhere is not a bad thing, Barrymore leaned in, placed her hands on him and replied, "That's wonderful, by the way. That's a good quality."
"Hey, I think so," Alwyn responded, before he and Barrymore excitedly agreed that it helps him boost his step count every day.
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While on the talk show, Alwyn also told a story about a childhood prank -- involving fake blood -- that ended with a Scotland Yard policeman yelling at him and one of his brothers.
"When I was about 8 years old ... I thought it would be a fun idea to prank the neighbors, and I wrote some letters. They were pranky, but they were of the threatening pranky kind, and they were dipped in fake blood from a toy store," Alwyn recalled, noting that the entire neighborhood became scared after finding the letters.
"Police cars turned up on the road 'cause they've got a killer to catch," he added. "I'm thinking I'm going to jail, and about three policemen came into the house, we had to confess to our crime and they stood over me and my brother, and because he's 18 months older, which is why it's great to have an older sibling ... he was the one that took the brunt of it. I don't remember what the policeman yelled at me, but they yelled."