How to Prototype Your Life: 21 Days to Test Habits, Routines, and Big Decisions

Here's a lesson from building software: Your assumptions are often wrong. And when they are, things can get very expensive—in both capital and time.

Stakeholders may have spent months, even years, building something unwanted. Now, it's irrelevant because it took too long to finish. We call this a waterfall approach. A long list of requirements becomes a sprawling to-do list and calendar. They never get finished on time.

Most of the time, designers avoid this pitfall. They make a lightweight prototype to get feedback on it. A prototype might be a shell of the final product. But it often looks and feels fleshed out enough to get the point across. These small and frequent tests are what make up the principle of agile development.

People often live their lives out in the waterfall method. They make massive decisions based on assumptions they never tested. Or worse, those decisions feel so heavy that they never make one. They get stuck in the valley of analysis paralysis.

But there's another way. The agile way.

Designing Your Life

I read a great book called Designing Your Life by Bill Burnett and Dave Evans. It was the first time I heard of prototyping in the context of experiences. Like a designer or engineer, we can rough out an experience instead of a product to gather insights from real-world use. We can do the same for new behaviors and routines. It will give us a fresh perspective and teach us a ton.

Once you embrace this idea, you'll see that you can prototype almost anything. Even better, the weight of a big decision is gone. The lightness and curiosity of an "experiment" or a game replace it. And best of all, it is a game you win just by making the choice to play.

Why 21 Days?

The beauty of 21 days is that it's long enough to try something new. It could be a habit, an activity, or a new mindset. It's enough time to get a meaningful taste of it, but not so long that it becomes overwhelming.

Shorter challenges might allow a glimpse. But, 21 days lets you experience natural ups and downs. You feel early excitement, then face the challenges of fading novelty. This time gives enough immersion to see if this practice works for you.

What You Can Prototype

Imagine if, before declaring a major, a college student had to spend 21 days shadowing someone in that field. How many fewer lawyers would there be today? I'm guessing a lot fewer.

What about that career change that has been on your mind for years? I bet there's a way to prototype that as well. Here are a few more:

1. Morning Routines

My current morning routine is a result of many, many 21 day experiences. I've tried many things. I went from alarms to no alarms. I did cold plunges for three weeks. I did early group cycling and gym workouts. I tried fasting, meditation, journaling, and deep work. See what works for you.

2. Digital Detox

Have you looked at the weekly screen time reports on your phone? Ouch. But yeah, I'm not ready to give mine up either. But you can try a modified digital detox by setting phone-free periods each day. Maybe just the first hour after waking up and the hour before bed. Use a journal to track how you feel at the end of each detox period and whether you notice shifts in your focus, productivity, or well-being over the 21 days.

3. Physical Fitness Routine

I've studied many movement practices, like trail running, strength training, martial arts, and yoga. Choose one you’ve been curious about. Commit to a light version of this routine (e.g., 15–30 minutes daily) to test its impact on your body and energy levels. Maybe you'll want to adopt it in the long term or make a variation of it that you never knew existed.

4. Dietary Experiment

Have you ever wondered how you'd feel on a vegan diet? A paleo or ancestral one? Or not eating at all for part of the day (intermittent fasting)? For 21 days, track your energy, digestion, and sleep. This will show how the diet affects your well-being and if it is sustainable.

5. Mindfulness Practice

For most of my life, the thought of doing "nothing" felt crazy, given how busy I always was. Little did I know that meant I stood the most to gain from a meditation practice. The beginning felt daunting, but committing to ten minutes a day for 21 days changed my mind. Back in the day, Headspace was the only game in town for a good meditation app, but there are countless others now. You can even find tons of free meditations on Spotify or YouTube.

Each prototype is a chance to find what works best. It allows for insights and adjustments in a low-stakes setting. This is before making long-term changes.

Learning through Real-World Feedback

Prototyping is all about learning by doing. In 21 days, you gain real experience. You don't rely on theory or imagination about how a habit might feel. Daily practice often reveals real-world feedback that people can't expect.

Maybe the habit you’re testing boosts your mornings. Or it may show you where to adjust your schedule to support it.

In the end, 21 days isn’t about arriving at perfection. Instead, it’s a practice of testing, adapting, and learning what suits you best. The result is insight. It will clarify if this habit is right for the long term. It will also show what changes make it sustainable and if it fits your designed life.