This fashion mogul may have created a billion-dollar business, but he says that being the boss is about character and muscle, not style.

Culture counts Marc Ecko believes in letting employees “own the vibe” of what they create: “That becomes your culture.”

How do you measure success?

Quantitatively and qualitatively. It’s not an exact science, but typically when people (your team and customers) are happy, you’re successful.

What’s one rookie mistake you made early on?

I still make them. You make rookie mistakes your entire career–hopefully just less frequently. One big one seems to be having too much pride and hubris. They can mess you up.

What was the hardest lesson you learned in your first year of business?

Learning to fire someone. It sucks. Trump makes it look so easy. Unless an employee is robbing you, it is never really that easy.

What’s the toughest part of being in charge?

Being in charge. You are accountable for people, places, and things. It’s full contact. It is also the greatest part of the gig, because it builds character and muscle.

What’s one skill you want to improve upon, personally?

Math.

What’s the best motivator for employees?

Authorship. Let them own the vibe of what they are creating. Celebrate it, quirks and all.

Whom do you admire most as a business leader?

Anyone with authenticity, especially my twin sister [and business partner], Marci [Tapper]. She is compassionate yet firm. She knows how to motivate you while keeping your feet on the ground and your head based in reality. She is an unsung hero.

Gut instinct versus expertise: Which is more important, and why?

That’s like asking “peanut butter or chocolate?” There is no adequate answer, so I’m not even going to try that one.