Like many veterans, Carlos Aguirre says he struggled to adjust to civilian life after serving in the U.S. Marine Corps for six years.

Aguirre, who received a Purple Heart after getting struck by an enemy sniper while serving in Iraq, says an interest in dog training – sparked by his platoon’s affiliation with a K9 unit – helped him get through a tough time after separating from the Marines.

“Dog training got me out of that rut of not wanting to do anything, and trying to stay away from people. Dog training definitely saved my life,” says Aguirre, who says many veterans think of themselves as invincible.

“As much as we cover ourselves up, we’re hurting inside.  It’s important to be able to accept the things that happened and not let them hinder you,” says Aguirre.

Today, Aguirre has turned his love of dogs into a growing business: Wolf’s Lair K9, a dog training company based in Northbrook, Illinois specializing in retraining aggressive dogs.

“We’re well known for ‘last chance dogs’ – dogs that are too aggressive or nobody else is going to take in. We’ve rehabbed and changed around a lot of dogs,” says Aguirre. The company also does normal obedience training for puppies, working closely one-on-one with owners to produce well-trained companions.

While the company is only one year old, Aguirre says he’s already planning to expand and add full-time employees. Over the course of a week, Wolf’s Lair K9 works with anywhere from 25 to 50 dogs.

“The really cool thing about dog training is it’s not just a product – we get to know our clients and how they think,” says Aguirre.

Now that Aguirre’s survived the first year of business ownership, he has some crucial pieces of advice for entrepreneurs looking to grow their businesses.

“As soon as somebody sends you an email, contact them right away – even if it’s late at night,” says Aguirre. And even though Aguirre says he works seven days a week, he says balance is key.

“Find time for yourself, so you don’t burn out,” he says.

Follow Gabrielle Karol on Twitter @GabrielleKarol