Everyone's had at least one run-in with a sucky boss, and Mark Cuban is no different.

35 years ago, Cuban was working at a retail store that sold software. He got the opportunity to make a $15,000 sale, so he asked a coworker to cover him at the store, and told his boss he was going to pick up the check.

His boss told him not to do it, but Cuban went ahead anyway -- he figured that his boss would be cool once he returned with a $15,000 check. But when Cuban got back to the store, check in hand, his boss fired him for disobeying orders.

According to Cuban, his boss at the software store was someone who tried hard to look and act the part of CEO. There was just one problem -- while he wore the right suits, he never did any work, and Cuban notes that he "never demonstrated the initiative to go out to sell".

After this encounter, Cuban came to realize the importance of caring about the actual results, not about appearances. He made the phrase "sales cures all" his mantra, and this came to be a phrase that would guide him throughout his journey as an entrepreneur.

And Cuban's ex-boss? Cuban says that he thinks of him as a mentor, but not in the way you'd expect. Even now, Cuban looks back on the things that his ex-boss did, so that he can do the opposite. 

Lead your team to be a lean, mean, sales-generating machine.

Like Cuban, I'm a firm believer in the idea that sales cures all. It doesn't matter how big your email list is, or how many followers you have on Twitter -- if you don't generate enough sales, there's no way your company will survive. 

Now, how do you lead your team to kill it at sales? To be honest, this is something that I struggled a lot with when I was building my company. 

In the early days, my sales reps were constantly coming up with excuses, and pushing the blame to their colleagues. If something didn't get done, for instance, they'd say that they thought someone else was taking care of it. 

At this point, I thought I had hired the wrong guys, and that I had to rebuild my team. But after talking to successful business owners and coaches, I realized that I was the problem. I hadn't communicated effectively with my employees up to this point, and I had to change this in order to get my employees focused on results.

I started doing three things with each employee: I'd sit down with them and first define what they were responsible for, second tell them what results I expected, and third set clear deadlines. On top of that, I also made sure my door was always open -- this way, my employees could see me for feedback, and figure out if they were on the right track.

It worked like a dream -- I no longer heard any excuses, and my reps started closing deals more effectively than ever before. We hit $100,000 in sales, then $1 million, then $30 million. Take it from me: focus on your sales (not on keeping up appearances), and everything will fall into place.