HOLLIS, N.H. (CBS) – Just leaving the house was scary and overwhelming for Massachusetts veteran Brian Callahan – until he found Maggie.

“She’s been a life-saver,” Callahan said of his beloved service dog during an interview with WBZ-TV at his Dracut, Mass. home.

As an active duty Marine, Lance Corporal Callahan served three overseas deployments.

When he came home, the enemy came with him in the form of post-traumatic stress disorder.

“Very anxious, very nervous especially at night, I couldn’t do crowds. I couldn’t do restaurants or anything like that. I suffered from night terrors. I heard something in the house and have to search the house,” said Callahan.

His struggle led him to Operation Delta Dog in Hollis, N.H., an organization that helps veterans struggling with PTSD.

The organization takes shelter dogs and trains them to be service animals for veterans.

This reporter is running the Boston Marathon to benefit Operation Delta Dog. As of 9 p.m. Saturday, Team Katie/WBZ runs Boston for Operation Delta Dog had raised $1,857 for the organization.

Lauran Burbridge, executive director of Operation Delta Dog, recently allowed WBZ-TV to tour their new training facility in Hollis, N.H.

“This is where we have our veteran dog classes. This is the safe space,” she said.

Labradors Belle and Walter are newbies. They will each undergo 12 weeks of full-time training at the facility. The dog then heads home with their veteran. The veteran-dog team works with a trainer and classes for another 12 to 18 months.

“They get to create the bond earlier on and really learn and grow together,” said Burbridge.

It costs Operation Delta Dog $25,000 to train, house and prepare each dog before they go to their new forever home with a veteran.

But the four-legged therapist costs the veteran nothing.

“It’s made it 100 times better,” said Alisha Callahan of the help that her husband’s service dog, Maggie, has given to him and their family.

Maggie is a calming force for the Marine veteran, by waking him up before a night terror and staying vigilant when they go out so he can relax.

“She’s given back my family. I get to go out with the kids,” Brian Callahan said.

The family even accomplished a trip that once seemed impossible: a trip to Disney World.

Judging from the vacation photos, it wasn’t just Brian who benefited. Even while working, Maggie had a good time too.

In Massachusetts and New Hampshire, there are around 100,000 veterans who suffer from traumatic brain injury and/or PTSD.