The star, 40, shared a photo of herself in a stomach-baring sports bra and leggings as she enjoyed a hike in the sunshine and while she looked raring to go in the snapshot, her caption suggested otherwise.
Rebel admitted to her fans that she hadn't had a good morning, but had forced herself to get out and exercise.
WATCH: Rebel Wilson opens up about weight loss and why she transformed her health
"Started off having a bad day," she wrote along with a sick emoji face. "But took myself on a giant walk, listening to some motivational podcasts & audiobooks (currently @antmiddleton The Fear Bubble) out in gorgeous nature...drank water...and you know what feel soooo much better now.
"We all have tough days but take a beat, take a nap and then get back out there and continue to crush."
Her followers flooded the comments section with compliments and gave her a much-needed boost.
Rebel is loving her 'year of health'
Many asked what other podcasts she has been listening to and she revealed: "Right now I’m listening to @fearnecotton and @jayshetty."
Rebel has transformed her health this year and she's certainly got the backing of her boyfriend, Jacob Busch.
She recently posted a swimsuit photo on Instagram from her trip to Mexico and it spurred the brewery heir on to make a rare public comment.
Rebel is dating Jacob Busch
He sweetly reacted with a fire emoji and flexed bicep emoji indicating he's incredibly proud of his girlfriend.
It's been a big year for Rebel who has powered through the ongoing COVID-19 pandemic with gusto.
Not only has she completely transformed her health, but she's launched a career as a children's book author, landed her first role in a non-comedic film and has just filmed a TV special with SAS instructor Ant Middleton.
It's a wonder she has time for her workouts!
Read more HELLO! US stories here
Like this story? Sign up to our newsletter to get other stories like this delivered straight to your inbox.