Deciding What to Build

Why are you building it?

I think there are three good reasons to build something:

1. Fun. Building is fun. Sometimes you just want to see whether you can make an idea work.
2. Money. Money is nice. You might want a side income, or you might want to build a business.
3. To help someone. You've noticed a problem and think you can do something about it.

They can overlap. You can enjoy building something useful and get paid for it. But it helps to know what you're actually hoping to get out of the project, because that changes which ideas are worth pursuing.

If you're building for fun, you don't need to turn it into a business exercise. If you want people to pay for it, though, there are a few more questions worth asking.

If you want to make money

Alex Hormozi has a useful framework for choosing a market in his teaching around $100M Offers. He looks for four things. ^[1]

• A painful problem. It matters enough that people want it solved. It's costing them something: time, money, frustration or a missed opportunity.
• Purchasing power. The people who need your solution have the money, or access to the budget, to pay for it.
• People you can reach. You can identify your target customers and find them through particular communities, channels or organisations.
• A growing market. You're looking at a market that's expanding rather than shrinking.

You could have a clever idea and still struggle because the people who need it can't pay, or because you have no practical way to reach them. These questions help you think about that before you've spent months building. They don't prove that your particular idea will sell.

Get more than a polite nod

When I first wanted to become an entrepreneur, I told people I was going to build a clothing brand. I got plenty of encouragement, but I always had a feeling that people were just being nice.

Pitch friends and family your next million-pound business idea and you'll probably recognise that feeling. The polite nod doesn't tell you whether someone has the problem, how much it matters, or whether they'd pay to solve it.

That's why I like The Mom Test by Rob Fitzpatrick. It teaches you to ask questions that produce useful information even when the other person wants to encourage you. The trick is to talk about their life and what they've actually done, rather than asking them to predict whether they'd use your idea. ^[2]

For example, if you're thinking about an app for personal trainers:

Then listen. Maybe it's a nightmare. Maybe their existing tools already handle it perfectly. Either answer is useful.

You have to detach your ego from the idea a little. Finding out that people don't have the problem you imagined can save you a lot of time.

Later, when you have something specific to offer, a real commitment—such as agreeing to a paid pilot—tells you more than “sounds great.” If target customers are willing to pay before you've built it, you may be onto something. It still isn't a guarantee, but it's better evidence than encouragement. ^[2]

Check the rules early

This is especially worth thinking about for mobile apps. Apple has rules about copycats, minimum functionality and spam, including apps that are indistinguishable from widely available offerings. Giving an existing app a new name and colour scheme may not get you very far. ^[3]

That doesn't mean every idea has to invent a completely new category. But do some research into the relevant store's requirements before you commit to building. Meeting an individual guideline doesn't guarantee approval.

Platform rules are only part of it. If your idea involves an industry with a lot of regulation, such as pharmaceuticals or medical services, find out which rules apply early. You want to understand those constraints while you're choosing what to build.

Decide what success means to you

One more book I'd recommend is Anything You Want by Derek Sivers, the founder of CD Baby. He encourages you to think about how you measure success, instead of automatically adopting somebody else's definition. ^[4]

For you, success might be learning a new skill, helping a small group of people, or earning enough to make the project worth continuing. You don't have to aim for the biggest possible business just because somebody else does.

Figure out what you want from it. That gives you a much better way to decide whether an idea deserves your time.

Books & sources

These are the books and original sources behind the ideas above. The book links go to Amazon UK and aren't affiliate links.

1. Alex Hormozi — $100M Offers. For thinking about your market and offer. Find the book on Amazon UK.
2. Rob Fitzpatrick — The Mom Test. For having customer conversations you can actually learn from. Find the book on Amazon UK.
3. Apple — App Review Guidelines. Start with 4.1 Copycats, 4.2 Minimum Functionality and 4.3 Spam. Checked on 19 September 2026; consult the current guidelines when planning your app.
4. Derek Sivers — Anything You Want. For deciding what you want your business to be. Find the book on Amazon UK.