Star calls Blac Chyna "my motivation"

READ: Rob Kardashian, Blac Chyna's wedding could make them $1M richer

Rob shared a flashback photo of himself looking heavier while standing next to Chyna as he gave her credit for being his motivation to slimming down.

"Looking from where I started 298lbs to my current weight now 248.4lbs . I'm focused and determined to reach my goal weight 200-205lbs," he wrote next to the snap.

"Happy I found my motivation," Rob gushed as he concluded the caption with Chyna's signature smiling devil face emoji.

READ: Pulse Nigeria readers believe Rob Kardashian's engagement is out of love

As we earlier reported, the former 'Keeping Up With The Kardashians' star is hoping to get to 200lbs by Chyna's birthday on May 11.

Chyna has even taken over as Rob's personal fitness trainer saying she's ready to train him every day with exception of her gig nights.

READ: Kanye West says he hasn't been invited to Rob Kardashian's wedding

Since he started dating the 27-year-old former stripper in January, Kim Kardashian's baby brother has been trying a healthier lifestyle including regular workouts and a healthier diet at Chyna's Encino home.