Gary Leff is a lot like many of us. He starts his day with email, managing his responsibilities as a CFO for two university research centers. It’s a good job that he enjoys, but the emails that come in during the “early early” morning are from a different venture entirely: his part-time consulting business. This is the reality of starting a side hustle while working full time.

Gary is what you’d call a “travel hacker,” someone who strategically earns hundreds of thousands of frequent flyer miles each year. Plenty of executives rack up miles, but there’s a huge gap between earning them and actually using them for a great vacation. They don’t have the time or knowledge to navigate the complex world of award travel. How many miles do you need? What do you do when the airline says no seats are available? It’s a frustrating process.

This is where Gary turned his passion into a side hustle business. For a $250 fee, he takes a client’s dream trip, mileage account, and travel dates and makes it happen. He dives into databases, calls airlines, and uses every loophole he knows to book incredible first- and business-class trips that would otherwise cost thousands. If he can’t book the trip, the client doesn’t pay. Last year, this side project brought in $75,000, and it’s on track to clear six figures.

Is Passion Enough to Start a Business?

Gary’s story is a classic follow-your-passion model. He was obsessed with travel, figured out a system, and started helping others. At first, he offered advice for free on forums and his blog. Soon, friends and acquaintances were asking for help, and he had more requests than he could handle. The next logical step was to start charging, and even with a basic website, his unusual service based side hustle took off.

But is building a business around something you love really that simple? The answer is a bit more complicated.

First, not every passion translates into a paycheck. You might love pizza, but it’s unlikely anyone will pay you to eat it. Your passion needs to solve a problem for other people. Mignon Fogarty learned this firsthand. Before she created the wildly successful Grammar Girl podcast, she had another show called Absolute Science. She was passionate about it and promoted it heavily, but it never gained enough traction to be financially viable. She didn't abandon her passion for podcasting; she just pivoted to a topic—grammar—that connected with a much larger audience.

Second, you usually get paid for helping others with your hobby, not for the hobby itself. Benny Lewis, a polyglot who runs the popular website Fluent in 3 Months, says he gets paid to learn languages. But that’s not the whole story. He actually gets paid for creating guides, videos, and courses that help other people learn languages. The inspiration is part of the package, but the business model is built on providing a helpful solution.

The Reality Check for Your Idea

Before you turn your hobby into a full-time commitment, it's wise to ask yourself a few tough questions. Could you happily spend twenty hours a week on it? Do you enjoy teaching others and dealing with the administrative details that come with running a business? If your hobby is a stress reliever, turning it into a job might ruin the very thing you love about it.

It's also crucial to look at the market. Are people already asking for your help? Is there a large enough group willing to pay for your expertise? The convergence of your passion and a skill that others value is where a real opportunity lies. This is how some of the most profitable side businesses get their start. Passion plus skill, aimed at a problem in a marketplace, creates opportunity.

Take Megan Hunt, for example. She started making custom wedding dresses at nineteen, determined to work for herself. Her creative side hustle grew into a full-time venture with employees, selling to clients worldwide. Like Gary, Megan monetized a passion, but she did it by selling a physical product. These examples show there isn't just one path. Gary offers a consulting service, Benny sells a digital product, and Megan sells custom goods.

The Quick-Start Guide to Consulting

If you have specialized knowledge, you can launch a consulting business in a day. It’s one of the best low cost side hustles to get going. The key is to follow two simple rules:

1. Be specific. Don’t just be a “business consultant.” Be the person who helps Etsy sellers optimize their listings for search or the person who helps small bakeries set up their local delivery system.
2. Don’t underprice yourself. No one takes a $15-an-hour consultant seriously. Since you won’t have 40 billable hours a week, aim for at least $100 an hour or a fixed rate that reflects the value you provide.

A simple website is all you need to get started. It should clearly state the benefit you offer, share a couple of stories of how you’ve helped others (do it for free to get testimonials if you have to), list your pricing, and provide a dead-simple way for people to hire you.

Taking Action Is the Most Important Step

Jen Adrion and Omar Noory, two design school graduates, were feeling burnt out from commercial work. They wanted a nice map to track their travels but couldn't find one they liked, so they designed their own. The printer had a minimum order of 50, which cost them $500. They hung one on their wall and, on a whim, put the other 49 up for sale on a one-page website.

They woke up to their first sale. Then another. After a mention on a design forum, they sold out in ten minutes. This happy accident turned into a side hustle to full time business. They didn't write a 50-page business plan; they had an idea, acted on it, and responded to what the market wanted. Their story proves that in the battle between planning and action, action always wins.

Their journey highlights a critical lesson for anyone starting a freelance business or product-based venture: the most significant hurdle is inertia. Getting that first sale, no matter how small, provides the momentum you need to take your project seriously. It’s proof that you’ve created something of value that a stranger is willing to pay for. Whether it's a consulting gig, a digital download, or a custom handmade product, the goal is to get to that first transaction as quickly as possible.