Tim Geary is a man on a mission — again.

The 77-year-old retired attorney from Aspinwall has resumed his hike on the Appalachian Trail in honor of his late wife, Gillen, who died after a seven-year battle with melanoma last year.

Geary, formerly of Vandergrift, began his hike March 17 at the trail’s terminus in Georgia.

An abdominal injury suffered while hiking the trail in April resulted in Geary halting his trek and making a decision to return to Aspinwall and undergo surgery to repair a hernia.

“My legs aren’t where they were,” Geary said from the trail in Boonsboro, Md., during an interview Wednesday. “It’s been 10 weeks since I’ve been on the trail, and the first two days back were really hard.”

He is hoping to raise more than $15,000 for melanoma research, a deadly form of skin cancer. He already has far exceeded his original fundraising goal of $5,000: he was up to more than $12,000 as of mid-week.

Geary aims to complete a solo Appalachian Trail “thru-hike,” which entails walking its 2,192-mile length within a calendar year.

If he succeeds, he will have walked through more than 10 states, concluding in Maine in October. The remainder of Geary’s route will include Pennsylvania, New Jersey, New York, Connecticut, Vermont, New Hampshire and Maine.

It takes the average hiker five to seven months to complete.

Thousands of hikers attempt to walk the Appalachian Trail annually, but only one in four complete the journey.

He boarded a bus Monday from Pittsburgh headed to Harper’s Ferry, W.Va., where he walked 6 miles to kickoff his return to the trail.

His first evening back on the trail included camping with three strangers in a primitive shelter. He said this week’s oppressive heat made for “brutal” walking conditions.

A trail highlight Monday was experiencing what Geary said is called “trail magic.”

Overheated and thirsty, Geary said he encountered a cooler filled with cold soft drinks Monday on the side of the path.

He helped himself to a lemon-flavored soda.

“A fellow hiking left that. I needed that cold drink,” Geary said. “Several times I’ve been hiking, people will cook meals on the side of the road for hikers. I’d like to be able to do that when I finish.”

He said his return to hiking in hot weather instead of cold temperatures has ushered in more potential dangers on the trails.

“The bears and snakes are out on the trail. I haven’t seen any yet,” Geary said. “The bears were still in hibernation when I first began hiking.”

Hikers on the Appalachian Trail like Geary use what is called a bear box — a metal container mounted on a tall pole that is high enough that the bears can’t reach the food — to keep their food safe.

Mealtime for Geary often consists of boiling water and adding it to a dehydrated meal such as stew.

“Ramen noodles are good, but I don’t like the protein bars, ” Geary said.

To stay properly hydrated, Geary collects water from streams along the trail, filters it and adds electrolytes.

Geary modified his backpack supply plan during his surgery recovery time because he realized his pack weighed too much, mostly because of too much food.

He reduced his pack weight from 32 pounds to 27 pounds.

His son, Brendan, called the interruption of his father’s hike a hiccup. He said he never doubted his father would be back on the trail after recuperating.

“He was very determined, and I’m confident he will complete this,” Brendan said.

Geary said he is hopeful he will reach his fundraising goal and is grateful for the support he has received from strangers.

“The generosity amazes me,” Geary said of the public’s outpouring of support and donations nationwide.

Brendan frequently updates his Facebook page with posts from the trail featuring “Papa Smurf” — Tim’s nickname on the trail, for members of “Gillen’s Army.”

Such names are a tradition on the Appalachian Trail. Geary said his 10-year-old grandson, Ryan Geary of Wisconsin, bestowed that nickname because of Tim’s trail attire of a blue shirt and red hat.

Geary said his strong Catholic faith is a source of comfort on the trail, and he often reflects on his 53 years of marriage to Gillen.

He served as her caregiver when she fell ill and said the couple discussed his desire to hike the trail before she died.

“I promised my wife I would dedicate this hike to her,” Geary said.