Pharmacist-Bodybuilder Builds Adaptive Fitness App in 8 Weeks

Pharmacist, competitive bodybuilder, and YouTuber Yim Yoon-seok has redefined fitness coaching with Alyak Coach, an adaptive fitness tracking app built in just eight weeks. Using AI platform Manus, Yim transformed his coaching workflow from labor-intensive spreadsheets into an automated system now serving 3,900 users and generating 6 million KRW (approximately $4,500 USD) in revenue as of April 2026.

Yim’s dual expertise in clinical pharmacy and bodybuilding has long been his calling card. A licensed pharmacist since 2016 and a competitive bodybuilder since 2018, he’s built a reputation for science-based training and supplementation strategies. However, his growing coaching business was becoming unsustainable. “I was spending more time on data entry than on actual coaching,” Yim said. Each new client required manual calorie and macro calculations, weekly updates, and extensive communication via spreadsheets and messaging apps.

A Doctorate in Pharmacy Meets AI Innovation

In early 2026, Yim discovered Manus, an AI-powered agent capable of writing and deploying code. Without prior programming experience, he used Manus to create Alyak Coach, a web-based app that tracks user data, syncs with platforms like Strava, and recalculates personalized Total Daily Energy Expenditure (TDEE) dynamically each week. Unlike static calculators, this feature adjusts based on real-time changes in users’ weight, workouts, and calorie intake—a game-changer for coaches and clients aiming for precision in their progress.

Yim’s pharmaceutical background provided a critical edge in explaining the app’s requirements. He used technical terms like metabolic adaptation and progressive overload directly with Manus, avoiding the need for simplification. By iterating on the AI’s outputs and refining his instructions, Yim overcame development hurdles that could have taken months with a traditional developer.

From YouTube to 3,900 Users

Yim launched Alyak Coach in March 2026, initially onboarding his existing clients. He soon leveraged his YouTube channel, where he regularly shares bodybuilding and nutrition content, to boost visibility. Organic growth followed as users recommended the app through gyms and group chats. By April 20, Alyak Coach had 3,900 registered users, with active subscriptions driving its revenue growth.

The app’s success highlights Yim’s knack for bridging science, technology, and fitness. His YouTube presence—coupled with his expertise in evidence-based supplementation and safe performance-enhancing drug (PED) use—amplified trust among his audience. Yim previously addressed PED regulation and nutritional pharmacology in South Korea, cementing his credibility in health and fitness circles.

Scaling Fitness Coaching Beyond Limits

An external developer had estimated a six-month timeline to build Alyak Coach manually, but Yim completed it in eight weeks with AI assistance. The efficiency allowed Yim to focus on growing his user base while maintaining his pharmacy career. The app’s mobile-first design also mirrored user habits, ensuring high adoption rates and satisfaction.

Today, the app automates the routine tasks that once consumed hours of Yim’s time, allowing him to focus on helping clients achieve their goals. “Every one of those users is someone tracking their weight, hitting their macros, and working toward a body composition goal,” Yim shared. “Now the system does it for them, adapting every week automatically.”

With nearly 5,000 users as of June 2026 and revenue climbing steadily, Alyak Coach exemplifies how AI can empower individuals to scale niche expertise into impactful businesses. Beyond bodybuilding, Yim’s story underscores the potential of AI to democratize software development, allowing subject matter experts to solve complex problems without needing to code.

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