This article originally appeared on Inc.

The best advice I ever got came from my boss at my first real, full-time job. He was giving his monthly corporate overview of the startup, discussing the company’s progress and describing its history. He recalled that when he started out, he had no employees, no clients and no revenue.

But he pitched every client like he was running a Fortune 500 company, and he embodied that attitude–both in the presentation of himself and of the brand.

And there it was: “Approach everything like you’re at a Fortune 500 company.” Just hearing those words made my spine tingle, putting all of my entrepreneurial aspirations, my anxieties and my drive into perspective. At the time, I was building my own business on the side, and that powerful mindset was exactly the inspiration I needed to pursue my goals.

I knew I had the chops and the courage to compete with some of the largest internet marketing agencies in the world, but I was still a one-man show. To combat that, I created the illusion that my company was a big shop, fully staffed with the best marketers in the industry. If my performance exceeded expectations, why should it matter what my head count was or how many square feet my office had?

As my company gained momentum, I realized that motivation, time and perseverance were all it took to get the job done. When you’re building a business from scratch, you don’t have cash flow, customers or even a staff to help you. The company’s success rests on your shoulders, so you can’t slack off for even one minute.

But if you take your work seriously, your clients will, too. This mentality has deeply impacted my success, and I continue to draw insights from it in both my professional and personal life. Even when I’m building a blanket fort with my kids, I immerse myself in their world. We’re not just creating a pile of blankets–we’re constructing a castle, cave or pirate ship. In the end, the looks on my kids’ faces are just as rewarding as landing that big client.

Here are the most powerful lessons I’ve learned from following my former boss’s advice:

1. Say ‘yes’ now, and figure out the details later.

When great opportunities present themselves, close the deal, and then strategize how to get it done. When a leading medical publishing company approached me to optimize its online repository of hundreds of scholarly journals, I knew the job was far too big for one person. But, I educated myself about their goals and created a blueprint for how we could work together to get it done.

As Richard Branson said, “If somebody offers you an amazing opportunity, but you are not sure you can do it, say yes–then learn how to do it later!”

2. Give 100 percent to your current position.

If you’re bootstrapping your new business while still holding down a full-time job, it can be a struggle to excel at both. (You can read how we did it here.) Be true to your vision, but don’t forget that your current employer is putting food on your table. Give 100 percent to your current job because you need something to fall back on in case your startup fails. In addition, that respect and loyalty will go a long way, and your former employer may become a client.

When I first started my own company, I was still working regularly; in fact, I spent five years bootstrapping my business while holding down another full-time position. I took calls in my car during lunch and used an old-school internet-tethering service on my phone to manage my startup’s online affairs and have remote web access. Although I wanted to focus solely on Teknicks, I needed the outside income to stay afloat. I also learned from my experiences while working full time, became more aware of ways to enhance my company, and adjusted my business model based on the lessons I picked up in the office.

3. Treat every opportunity like it’s your big break.

When you do this, you treat every client with the highest regard, providing a level of attention customers always hope for–but rarely receive. That kind of service differentiates you from your competitors.

One of my earliest customers was acquired by doing just that. Before becoming a client, they reached out for advice on revamping a landing page for one of their major publications. Instead of firing off a few quick ideas in an email, I asked a friend who was a graphic designer to mock up two new variations of the page, and I wrote a detailed explanation of how each would optimize the conversion process and generate more leads and subscribers.

I could have spent five minutes on that initial email providing some pointers, but I went the extra mile. That client ended up becoming my biggest account, spending millions of dollars with my agency during the next few years. That was the break I needed, and it would have slipped by if I hadn’t treated it as such.

When you’re first starting out as an entrepreneur, it’s easy to get preoccupied with the notion of your ideal client persona. But that mentality can blind you to the opportunities you have with the smaller accounts you’re generating early on. Go into every meeting and contract with the intention of delighting your customers, and your company will be better for it.