This project was created during a three-day hackathon in late 2020, where I worked as a UX designer for the first time. With no prior experience and little time, I relied on desk research and quick prototyping to design a fitness app supporting mental and physical well-being during the pandemic.
Though the process lacked structure and accessibility considerations, our team won first place in the Rakuten API track. This experience gave me the confidence to pursue UX design — and a lasting awareness of how much better design can be with time, reflection, and inclusivity.
Challenge
Junction X, organized in Finland, stands as one of Europe's largest Hackathon organizers and also operates a branch in Seoul where I joined a three-day hackathon at the peak of the pandemic. At that time, South Korea’s restrictions limited gatherings to four people, therefore all collaboration had to happen online.
The challenge was to design an application that addressed pandemic-related needs using a provided set of APIs. I connected with teammates through Slack, and we chose the Rakuten API track to develop an iOS app supporting both physical activity and mental well-being at home.
Research & Key Features
Desk research revealed three key insights:
A surge in the home workout market
The loss of social interaction due to distancing
A sharp rise in depression and mental health concerns
To respond, we focused on features that promote movement and connection without physical proximity:
Competition: Inspired by research showing a 90% increase in engagement through competition, we introduced friendly challenges.
Real-time matching: Using the iPhone’s proximity sensor, users could compete live from a distance.
Mental health support: By encouraging routine and social connection, the app aimed to reduce isolation.
These became the foundation of a more engaging and emotionally supportive fitness experience.
Design Concept
Once the technical components were defined — Rakuten’s BMI and Facial BMI APIs and the iPhone’s proximity sensor — I focused on creating a visual and interaction concept that felt dynamic, competitive, and emotionally connected.
I framed the experience around three core ideas:
Matching: Having fun through friendly competition
Exercise: Fast, focused, and rewarding movement
Connected: Feeling close, even while physically apart
To reflect these values, I used bold visuals, vivid colors, and clear motion cues throughout the interface.
UI Design
Training
Users can watch instructional videos for at-home training or follow expert-led exercises like push-ups, squats, lunges, and crunches
Activity
The user can view attendance frequency using color codes, track daily activities like steps, sleep duration, and burned calories through integration with the iOS Health app. They also receive analysis on exercise results and can match progress with friends.
Training
Users can watch instructional videos for at-home training or follow expert-led exercises like push-ups, squats, lunges, and crunches
Activity
The user can view attendance frequency using color codes, track daily activities like steps, sleep duration, and burned calories through integration with the iOS Health app. They also receive analysis on exercise results and can match progress with friends.
Before Match
Before the match begins, select a workout and an opponent to compete with
During Match
The proximity sensor in iPhone counts the number of times in real-time. The match will proceed until someone gives up first
After Match
The user can see who won the game, the numbers of each other, and the calories consumed
Reflection
This project is especially meaningful to me because it marked the beginning of my UX journey. It was my first-ever hackathon, and I felt incredibly rewarded when we won first place in the Rakuten API track. With only three days to conduct desk research, design, and hand off to developers, the process was intense — I stayed up for almost two nights straight.
Looking back, I recognize that the approach was not as structured or inclusive as I would pursue today, such as small font sizes or not enough color contrast. However, it taught me a powerful lesson early on: that meaningful outcomes can still be achieved under constraints, through collaboration, focus, and shared passion.
This experience gave me the confidence to move forward as a UX designer.