This as-told-to essay is based on a conversation with Robbie Cartwright, founder of Yorkshire Trainers. It has been edited for length and clarity.

I’ve been selling things since I was a child: candy bars, fidget spinners — you name it.

My middle school had a challenge to see which student could take a small investment of about $10 and make the most profit. I won, selling hooks to hang handbags on. I profited more than $1,000 over the six weeks of the challenge, although it was all for charity.

By the time I was about 14, I was reselling sneakers. Some kids have hobbies or play sports, but I would troll eBay, looking for deals that I could make a profit on. I reinvested what I made, and soon started camping out in line for exclusive sneaker drops. I might spend $200 on a pair of sneakers from the factory, then resell them for $1,000 later that night.

That was my whole weekend: sourcing items to sell. Sometimes I could convince my friends to come camp outside stores with me. My parents weren’t too keen on the idea of me sleeping outside overnight, but they let me do it. I believe it made me a tougher person.

I’m making tons of money, but that’s not what motivates me

If I sold three pairs of sneakers, I’d use the profit to buy five more. I viewed selling as more of a hobby than a job. Still, it was taking up a lot of my time. I didn’t study much and found any excuse I could to get out of school. By about 17, I was all in on the business.

That was four years ago, and the business has grown massively. Today, I do five figures of sales each month, and in May, I hit a record: more than $280,000 in one month.

Money isn’t my main motivator. The industry of reselling online via live-streaming is still young, especially in the UK, where I’m based. I’m chasing that top spot in the industry because it’s still up for grabs.

Friends have drifted because I’m so focused on work

Being so dedicated to work impacts all areas of my personal life. I used to go to watch my favorite football team with my friends every week. Now, I haven’t seen a game in probably three years.

Unsurprisingly, my friends have drifted away. I’m not still friends with anyone I went to school with. I did a vacation with a new group of friends and had a great time, but for the next two years, I didn’t want to take time off work to join their trip.

I just turned 21, and my parents hosted a party beginning at 5 p.m. on a Sunday. I worked until 7, and was late to my own birthday. My parents wish I wouldn’t work so much, but I’m all gas, no brake. I figure that I can be on a yacht at 40; I don’t need to be there at 20. I want a family, eventually, but not for a long time.

I don’t see myself slowing down

Since I’m working all the time, I don’t spend much money. Despite selling high-end sneakers, I don’t spend much on clothes for myself. I’m wearing a $30 pair of sneakers today, and they’re worn out. I also still live at home with my parents. I’ll do that until they kick me out.

Last year, I bought two rental properties. I paid cash, so I don’t have a mortgage. Other entrepreneurs have told me to invest when I’m young. Real estate is my way of doing that. I’ve invested a little in stocks, but mostly want to stick to what I know, and that’s real estate. I’m a simple man.

Too many people my age are focused on instant gratification, but I’m the opposite: I want to build my wealth now. I get my thrill from watching the business grow, not from spending money.

Right now, I’m happy working full throttle. I’ll do that until I hit a wall. I don’t see any reason not to. I know I put a lot of pressure on myself, but I’m young — I have time to make mistakes.