Cailyn Yong

I think the real start was around February this year.

January: decided to start a company

February: incorporated the Korean entity and submitted an idea to a startup competition

March: started building a “no-code agent building platform for non-developers”

April: kept building, but pivoted for a few reasons:

May: after the pivot, I uploaded a YouTube video introducing an idea called Momo, an AI personal assistant. Around 20 people signed up, each paying $3. I built the prototype in a week and tested it. The feedback was, “It’s good, but not something truly innovative or necessary.” What I realized was that I wasn’t building for people who really needed it, and I didn’t have a sharp use case.

June: made the second version as a desktop app. But I hadn’t figured out the core issue yet — no clear target, no sharp use case — so it failed again. Wasted time. For some reason, I felt like I should raise money, so I started talking to Korean VCs. All of them rejected me.

Then, by total coincidence, one of the people who had signed up for the first version of Momo turned out to be the CEO of Jenni.ai.

July: started working full-time at Jenni.ai’s office. Right after the funding round, my confidence was at an all-time low. I wondered if I should pivot again. But seeing how much the Jenni.ai CEO genuinely needed a personal assistant made me realize that maybe I should focus on founders like him. So I started interviewing founders and decided to become someone’s assistant myself. Through a friend, I began working as an assistant for a startup founder in SF (Alljoined).

August: started working with a friend I’d been trying to convince to join me. The third version of Momo was supposed to be an email labeling and prioritization system, kind of like Superhuman. We worked together for 2–3 weeks, but communication issues kept delaying progress. I got super stressed and burned out. Then, for no clear reason, I just felt like I needed to go back to San Francisco, so I did.

While I was there, I realized I’d been building the wrong way. You should sell first, validate the idea, and then build. After that trip, I started thinking deeply about what founders really struggle with.

It’s the constant context switching and the chaos of too many threads. It’s impossible to manage. Even with all the email labeling systems in the world, that problem wouldn’t go away.

So now I’m working on the fourth version of Momo — a system that connects all inboxes (email, Slack, WhatsApp, LinkedIn, etc.) in one place. Momo, the AI assistant, automatically categorizes each message into to-dos or follow-ups, and keeps reminding you through Slack DMs.

I finally made my first sale for $99 with this idea.

I’m working on the MVP with another backend engineer, and we plan to finish it before Chuseok next week. Funny enough, Chuseok is right before my birthday. Hopefully my birthday present will be a finished MVP, lol.

Anyway, that’s how the past few months have gone. Now I want to share some lessons I’ve learned along the way from all the people I’ve met.

1. Startups don’t die because they don’t have a product or users. They die when the founder burns out.

That’s why mental health is everything.

2. Trying to bring someone in to fix your problems or looking for shortcuts is a waste of time and money.

The only real shortcut is doing it yourself.

3. Something I learned from InBody’s CEO, Mr. Cha:

A founder’s job is to quickly and skillfully solve problems they’ve never faced before.

It’s like asking someone who’s never played soccer to go score a goal.

To get good at that, you have to build small wins, one by one, apply what you learned, and repeat.

My small wins so far:

YouTube channel: 2,600 subscribers (in about 1–2 months)

Instagram: 5,700 followers (in one month)

First sale

Secured angel investment, joined an SF hacker house, became part of the Sigma Squared founder network

So far, I think I’ve just been building the foundation. Now it’s time to start stacking real product wins on top of that.

I’m good at building communities and gathering people, so I want to find ways to apply that skill to sales, GTM, and distribution.

4. If you go 10 times, it’ll sell.

There’s no tree that won’t fall after 10 chops.

My first sale actually happened within two meetings. The first was a user interview back in June. In September, I reached out again for another meeting. Before the call, I researched the person’s background like crazy and quickly built a lovable prototype based on the pain points they shared last time. During the call, I sent the Stripe link and they paid right away. Since it worked once, I just need to keep doing the same thing with other founders. Whether it takes two tries or ten, I’ll keep going.

5. I recently met Woohyuk, a staff member from the alarmy CEO’s office.

He taught me how to work more efficiently and systematically, and it honestly helped a lot.

My head is usually a mess. Sometimes I can’t even organize my thoughts or figure out where to start.

He looked at my current MVP process and told me to write down every detailed feature clearly, and since MVPs tend to spiral endlessly, to define exactly where to stop. So I wrote everything in a doc, connected it to Linear MCP through Claude Code, and asked it to create issues in Linear automatically. Now I work off Linear, and it’s been a game changer. My brain feels clearer, and I can instantly see how everything’s progressing.

6. Along the same lines, Mr. Cha also said:

Most founders spend 90 out of 100 hours doing useless things.

So building a startup isn’t about just working “hard,” it’s about working smart and thinking deeply about what actually matters.

Until now, I’ve just been working hard without any real structure.

So from now on, I’ll list out everything that needs to be solved, then tackle them one by one with 100% focus.

Multitasking isn’t a strength, it’s a trap.

7. To hire good people, find ones who’ve achieved small wins on their own.

People who’ve only worked in structured environments often don’t know how to handle problems when you ask them to.

Someone who’s achieved something alone, even something small, performs 150% better.

That process of failing and succeeding is real experience, and that’s what matters most.