Stretch — a guided mobility workout for iPhone and Apple Watch.

Stretch is an iPhone and Apple Watch app that turns a mobility routine into a guided workout. It breaks each exercise into clear steps, manages timed holds, remembers completed sets and keeps the next action easy to find.

Why I made Stretch

I wanted to incorporate stretching and mobility into my workout routine, so of course I asked ChatGPT to put one together for me. The next step was to find an app on the App Store that I could use in the gym. Everything I saw either looked terrible, was abandonware designed for iPhone 8, or had an unnecessary recurring subscription. And none of them seemed to have the one obvious feature I actually wanted: the ability to control my workout from my watch. So I just built it.

What I did

Initially I put together a native iOS app with an inbuilt routine, Apple Watch companion, and Apple Health integration. After using it for my first workout, I refined the flow and some of the views, and realised I had something far greater than anything else I had tried.

To submit this to the App Store, I needed to include a way that would allow people to add their own exercises and routines. I absolutely did not want to create a routine builder where people had to search an inbuilt library, choose an exercise, enter the reps and duration, and repeat the process over and over again. I’ve wasted many hours of my life adding whole weekly routines to other weightlifting apps.

Rightly or wrongly, so many people today go to their agent of choice and ask them to build a workout routine to meet their fitness goals. So I decided just to lean into that. To add a custom routine to Stretch, users copy a prompt from the app and paste it into their agent. They can include an existing routine or ask for a new one, then paste the JSON output back into Stretch. The app flags any errors and lets them confirm the import alongside the three curated routines that ship with the app.

Because Stretch is a fully native Swift app, I thought, why not make the most of Apple’s built-in technologies? Things like Live Activity, App Intents, Shortcuts and so on. Other apps I tried see the OS as an inconvenience, and I thought I’d go all in and make it a best-in-class app, adding full accessibility options and keeping it up-to-date with support for devices like the iPhone Duo.

For a fun experiment, I decided to price the app as a traditional paid app at a nominal cost. Simply put, I didn’t want to bother with creating an in-app purchase flow or figuring out trial periods and feature limits. Sales of Stretch have already surpassed my expectations.