GROTON -- For Sandra Hersh, the journey to discover what life has to offer starts with walking through her neighborhood with her friend Denise Johnson to experience "the things you miss when you drive by."

The "things" could be roadside lavenders that make Hersh stop to smell or the morning glories blooming around someone's mailbox that Johnson marveled at the other day. Or it could be a total stranger like Perry Johnson, a retired electronic technician who stepped out of his Pleasant Street home to find the two women walking by and asked what they were up to. Two minutes into their conversation, Hersh realized she and Johnson had met the cheerful 88-year-old once before.

"Lance is your son! We met on the trail," Hersh told Johnson, who has no relation to Denise Johnson. In an instant, the three began talking like old friends.

Running into people like him has made it worthwhile for the women to walk every single street in Groton during the past 40 weeks, Denise Johnson said. And after finishing up the last street Wednesday, they are more eager than ever to expand their walking territory.

"You really have to be outside," Hersh, an after-school enrichment class teacher, said. "You just have to be able to enjoy what you have in your town."

Looking over the buildings along Route 119 and the mountains over the horizon from Skyfields Drive -- a hilly street that they had saved as their last one to walk on -- Hersh and Johnson pondered what to do next now that they've wrapped up their project.

"It's bittersweet," Hersh said, looking back on countless neighbors she and Johnson met while walking.

Hersh, who has lived in Groton for more than two decades, and Johnson, a retired teacher from Ayer, met three years ago through a local walking group that ceased to exist. The two women had been regularly walking on the Nashua River Rail Trail together when Hersh came up with the idea to check out all Groton streets last October.

"The idea was still to have fun and see what we would discover," Johnson said.

Their once-a-week walking session lasted up to three hours at a time. They would sometimes leave one of their cars at their destination to drive back, and Hersh would mark off the streets they have conquered.

"It took some planning," Hersh said.

But their journey would always take unexpected turns. In the Lost Lake neighborhood filled with small winding roads, for example, they once forgot where they had parked. While trying to find their way in the neighborhood on another day, though, they heard Christmas music, which they traced to local historian Earl Carter's house. They discovered an animal farm on his property that they didn't know existed, Hersh said.

In another part of town, Hersh and Johnson stumbled onto the Groton Fairgrounds that they had only heard about and crossed nearby Fitch's Bridge, an antique footbridge over the Nashua River. They also peeked through the windows of Shanklin Music Hall on Sandy Pond Road, which is known for its pipe organ.

Catching sight of rock legend J. Geils coming out of his garage in his car during one walk excited the two women like teenagers.

They also learned to be thoughtful drivers after walking along routes 119 and 225 and feeling the impact of the cars going by, Johnson said.

Whenever reaching borders with surrounding towns -- Westford, Littleton, Ayer, Pepperell, Townsend, Shirley and Dunstable -- they made sure to walk to the line, Johnson said. They now consider themselves experts in giving local directions.

Residents sometimes looked at the pair strangely, Hersh said. Once folks found out about their walking project, however, they wanted to know more. They would ask why they wanted to walk all the streets.

"The biggest question was how many miles (we had walked)," Johnson said.

Having never used pedometers, they couldn't answer the question. But they know the distance they logged can be measured in the sights and sounds now seared into their memories.

Hersh, who grew up in Lowell's Highlands neighborhood, and Johnson, who used to teach at Sullivan Middle School in Lowell, are considering walking across Lowell.

In Groton, "every person we met on the way was nice," Johnson said. 

And they hope the experience will repeat itself.

Follow Hiroko Sato at twitter.com/satolowellsun.