Cassey Ho from Blogilates Challenged Brie Larson to Do 100 Sit-Ups In 5 Minutes

Brie Larson knows a thing or two about seemingly impossible fitness challenges. Not only did she get into actual superhero shape to play Captain Marvel, but she once literally scaled a 14,000-foot mountain like it was NBD. However, she just tried one challenge that straight-up terrified her.

Dressed in a colorful athleisure set from the New Balance x Staud collection, Larson teamed up with Cassey Ho, the founder of Blogilates, for a video on Larson's YouTube channel in which the pair attempted to do something neither had ever tried: 100 sit-ups in five minutes. (Eep.)

In the video, Larson and Ho truly didn't seem sure if they could pull it off. Larson, who has conquered indoor rock climbing, pull-ups with steel chains, and 400-pound hip thrusts, said her stomach hurt just thinking about doing that many sit-ups (same, TBH).

Spoiler alert: Larson and Ho crushed the challenge. How, you might ask? Aside from a lot of grimacing and shouting, the pair made sure to maintain proper form. They stabilized their bodies by keeping their feet weighted under something (in their case, dumbbells, but you could also keep your feet under a couch, or someone could hold your feet down, suggested Ho), and they were careful not to pull on their necks each time they sat up. (FYI: Fitness challenges are a fun way to test your strength, but here's why sit-ups aren't the best ab exercises to do.)

The two also cleverly distracted themselves from the struggle of doing 100 sit-ups in 5 minutes by chatting and getting to know each other. Ho marveled at Larson's incredible strength (particularly that time she pushed a jeep uphill), and the Blogilates founder shared her proudest physical achievement (her flexibility). Before they knew it, the two had completed the challenge in an impressive 3 minutes and 30 seconds.

Over on Ho's Blogilates channel, the pair teamed up for a separate "superhero abs" workout video. Yes, you read that right — they worked their abs more, immediately after completing their "100 sit-ups in 5 minutes" challenge. In Ho's video, they conquered some Pilates roll-ups (a favorite of Kate Hudson's), leg lifts, single-leg jackknife splits, and more, all with slow, controlled, strong movements — despite their obvious soreness from filming the video on Larson's page.

Whether you're watching the pair do 100 sit-ups in under 5 minutes or admiring their strength in Ho's "superhero abs" workout, these ab exercises can all be done practically anywhere using just your bodyweight. (Here's why core strength is so important.)

Looking for more fitness challenges? Try our 30-day ab challenge to build a stronger core.