Thomas Weller has two gardens - one in his backyard, where he grows morning glories and other plants - and one on the highway, where he sows the seeds of kindness, CBS News correspondent Steve Hartman reports.
"There's too much anger and distrust and fear out there. I'd like the world to be a better place," Weller said.
To that end, Weller patrols the highways of San Diego in his Ghostbuster-inspired rescue vehicle - rescuing people like Mr. Frazzled and Ms. Frustrated here.
The couple was overheated - as was their car.
"It don't look good," Weller said.
"Not good," the woman in the car said.
Fortunately, this was their lucky day. A mechanic by trade, Weller is prepared for just about any roadside emergency.
"This is way better than AAA," one woman he helped said.
He helped one couple, first to find their spare tire - then change it.
"I never would have figured out you unscrew it!" the driver Weller helped said.
Of course, eventually, people will ask him, "Why are you doing this?" To which Weller responds without saying a word.
"He gave me a card," one woman said. "It says, 'Assisting you has been my pleasure. I ask no payment other than for you to pass on the favor by helping someone in distress that you may encounter.'"
It's the same message Weller first heard 40 years earlier almost word-for-word, after he plowed his car into an Illinois snow bank.
"I probably would have froze there if this fellow hadn't stopped to help me," he said.
Since then, Weller has paid the favor forward more than 5,000 times.
After one stop to help a man change his tire, Hartman asked Weller: "He's a strapping young man. He could have changed his own tire."
"Sure he could have - but then I wouldn't of had the fun of doing it for him," Weller said.
Weller says it's a great feeling. Of course, on rare occasion, some other good Samaritan will beat him to the punch.
In fact, that happened not long ago - and Weller actually asked the do-gooder why he stopped to help the stranger.
"He said four months earlier his wife had had a blow out on the freeway - and somebody stopped to help her," Weller said. "And he said, 'By the way, thank you for doing that for my wife.'"
Obviously, somebody had read his card.
"So you saw it all come full-circle," Hartman asked.
"That's my garden growing," Weller said.
And who knows how many other offshoots have come from this devoted gardener, who plants seeds of good deeds in the fallow field of the American freeway.