This story is part of CNBC Make It's Millennial Money series, which details how people around the world earn, spend and save their money.

After graduating from Syracuse University in 2017 and spending three years working corporate jobs in both advertising and marketing in New York City, Vienna Hintze wanted a change.

In 2020, the then 24-year-old struck out on her own and created her own digital marketing agency. In September 2022, she moved to Los Angeles while running her agency from her apartment, but still found herself longing for something more.

"I was kind of losing the why behind what I was doing," she tells CNBC Make It. "I had moved out to L.A. and something just wasn't working anymore. I had changed everything about my life except my agency."

That restless feeling led to a talk with her therapist, who advised her to create a list of what she wanted from her ideal job. Hintze listed out that she wanted to work with her hands, be outside interacting with people and that she'd love to own an old pickup truck.

About a week later, she came up with the idea to start her own flower truck business, Main Street Flower Truck.

Since launching in August 2023, the business has brought in around $44,000 in revenue, plus an additional $4,500 in cash, Hintze estimates.

In May 2024, the now 29-year-old's business brought in around $16,000 that month alone.

"If you're living with your happiness, the money will follow," she says.

Finding the perfect flower truck

Hintze grew up in Long Island, New York, and her father used to commute to his job as a firefighter in a pickup truck. Her mom held many different jobs but her love of gardening was a mainstay, Hintze says. So both the vehicle and the bouquets were familiar to her.

"Growing up, she had the entire backyard blossoming and blooming constantly," Hintze says. "And some of my favorite memories with my dad was driving around in his little pickup truck."

She decided to name her company after the street where she grew up, Main Street. But before she could move forward, she needed to obtain a key element: the vehicle.

Since she was still running her digital marketing agency full-time, she had only looked at, and taken test drives in, a few potential trucks. Eventually, by accident, she stumbled upon the perfect one.

When her parents came to visit her and her sister in Los Angeles last May, they decided to drive to Ojai, a small town in Ventura County about two hours outside of the city. While cruising along a back road, she spotted a bright green pickup truck with a for-sale sign in the window that looked similar to the one she drove while in high school.

"This felt very meant to be," she says.

After the family pulled over to inspect the truck, Hintze wrote down the number on the for-sale sign. She called the owner that same day to ask if she could take it for a test drive. The seller agreed and told her that she had just replaced the engine and the transmission.

"I put my hands on the hood of the truck and just had this thought to the universe saying, 'Please, if this is meant to be, please give me a sign.'"

The universe delivered: The owner told Hintze that the truck's name is "Fiona."

"My name is Vienna and every time I have introduced myself to someone in L.A., only in L.A., they've all asked me if I just said 'Fiona'," she says. "So that was my sign that, absolutely, I need to buy this truck."

Two weeks later, she purchased Fiona for around $10,000 using money from her personal savings. Although she felt nervous about whether the flower truck would be successful, she was confident in her ability to run her own business.

"As scary as it was to pull the trigger on the flower truck, I already knew that I was the type of person to be all or nothing on whatever I do," she says. "I was going to be 100% dedicated to it, and anything it takes to make it work I was going to definitely do."

From side hustle to full-time flower selling

In August, Hintze began selling flowers from her pickup truck on the side while running her digital marketing agency. But as business began to pick up for her flower truck, clocking in for her marketing job got harder.

"It was like pulling teeth to get me to log in every day," she says.

She knew she had a decision to make: Should she focus on running the flower truck full time, or her marketing agency? By February, she made the choice to pour all of her time and energy into growing her flower truck business.

Hintze decided to put her advertising and social media marketing skills to work for her own brand, and saw the results of her efforts pay off a few months later in April.

"I had some content start to go viral which felt incredible because, for the first time, I was marketing my own brand and it was the most authentic thing I had ever done," she says.

That's not to say Hintze hasn't faced unexpected challenges. Since she spends thousands purchasing flowers, she used trial and error to figure out how much she should charge in order for her business to be profitable, for example.

"[At] the very first pop-up, I was selling huge bouquets for $7 and lot of that was just to prove to myself people will buy these bouquets, keep going," she says. "I definitely lost money that day, but that's OK."

How the flower truck business makes money

Her flower truck business brings in money in three ways, Hintze says: through pop-up events, corporate bookings and video shoots.

At pop-up events, she drives her truck full of freshly picked flowers that she's arranged into bouquets to various locations around Los Angeles. She sells them for anywhere between $10 for a mini bouquet to up to $75 for larger custom arrangements made right on the spot.

"It's always really fun to hear about whoever's receiving the bouquet because then I customize it based on what they might like and their personality," she says.

In between pop-ups, she books corporate events, parties and weddings. So far, she's worked with a number of companies, including Lululemon, Free People and Universal Music Group.

For these events, the company or person can choose to rent the truck without flowers; rent the truck with flowers that can be sold to attendees; or rent the truck and pay for the flowers up-front to be given out to attendees for free. For these events, she charges based on how long they're booking the truck and how many flowers they'd like to purchase.

Since flowers are seasonal, she earns more money in some months than others. Sales tend to fluctuate around holidays like Valentine's Day and Mother's Day, she says.

In general, Hintze aims to book at least three events each month, which she says generates enough money to cover her living expenses. However, she tries to keep her personal expenses low so that she doesn't outspend her earnings.

In May, however, Hintze had the most bookings since she began her flower truck business. She booked 10 events and brought in a little over $16,000 in revenue.

"I'm hoping to keep that momentum up for the rest of the year," she says.

A breakdown of monthly expenses

Here's a look at the Main Street Flower Truck's expenses for May 2024:

Hintze's largest expense is flowers, which totaled about $2,304 in May.

Before a pop-up or other type of event, she swings by her local flower district to choose which flowers looks the freshest and brightest, she says.

"I always gravitate toward wild flowers and things that look very whimsical and fairy-like," she says. "I think it makes it the most fun-looking setup for the truck."

She then brings those home and begins prepping them for sale by removing leaves, thorns and cutting stems. Finally, she arranges the flowers into bouquets and places them into various vessels, such as antique milk jugs and vintage buckets.

Her other expenses come from gas and maintaining her pickup truck. While the truck hasn't needed any expensive repairs since she bought it, occasionally, she's had to learn how to fix mechanical issues on the fly.

"One of the biggest issues having an older truck is the amount that it breaks down and having to randomly jump start it the morning of a pop-up when you're set to be there at a certain time," she says.

'People ask me a lot if I'm going to franchise'

Moving forward, Hintze plans on continuing to grow Main Street Flower Truck and help companies and individuals bring their floral dreams to life. But she isn't thinking about expanding her one-woman business yet.

"People ask me a lot if I'm going to franchise the truck and have a fleet of flower trucks, and I don't see that being the plan for maybe ever, but definitely for a while," she says. "My goal is to have the flower truck be as successful as it can as its own standalone, and see how far that can go."

She hopes that the truck can be featured in TV shows or movies one day. "In the future, I'm hoping that Fiona will have her red carpet moment," she says.

Hintze plans to continue to enjoying the freedom and work-life balance she's gained by starting Main Street Flower Truck.

"I'm excited to keep exploring the creativity that I have that was pushed away for so long and really develop a routine out here that keeps my peace of mind at the forefront," she says.

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