Robert Redford plays writer Bill Bryson and Nick Nolte plays his friend, Stephen Katz. (AP)

With a movie title like “A Walk in the Woods,” you may think you’re in for something of a leisurely stroll, but the woods in question are on the rugged Appalachian Trail. And the walk is really a very serious hike that requires a heavy-duty backpack, with tent, utensils, maps and a first-aid kit.

What distinguishes this particular walk from many others on the Appalachian Trail is that the walker is famed travel writer Bill Bryson. At a somewhat advanced age, he decides to take on the monumental task of walking the entire trail.

“I’m tired of life being all about ailments and funerals,” he said. “I want to push myself.”

“You want to hike the Appalachian Trail? 2,000 miles? You have gone mad,” his wife exclaimed.

That’s Robert Redford playing Bryson and Emma Thompson, his wife. She’s convinced he’s too old to do it alone and insists he at least find a fellow hiker to go with him. When an old alcoholic buddy from college agrees to go with him, she’s less than thrilled. And after seeing his friend for the first time in years, Bryson himself has his doubts.

Nick Nolte plays this old friend (Stephen Katz) as a larger than life “walking disaster,” but somehow the two men manage to have a grand adventure on the trail. And yes, Bryson wrote a best-selling book about it. And now there’s this movie.

What’s odd is that Bryson and Katz were 44 years old when they took on the trail and yet they’re being played by 79-year-old Redford and 74-year-old Nolte. I haven’t read the book, but I have to believe that a 30-year age difference has to change the tenor of the trip the two undertake.

Watching a couple of 70-year-olds dealing with the physical travails of surprise snowstorms, climbing accidents, and marauding bears can’t possibly be the same as seeing a couple of 40-somethings tackling the same tasks. And then there are all those aggressively flirty women they encounter on the road too.

I’m sure when they were in their 40’s, Redford and Nolte had women falling all over them, but c’mon, they’re almost 80! I suspect something’s been lost in the translation.

Perhaps because they are the ages they are, their adventures seem tame and amusing rather than dramatic and expansive. More Laurel and Hardy than Lewis and Clark.

At one point, Bryson says the Appalachian Trail is a lot like life &#8212 you don’t know what’s going to happen next, but you give it your best shot. It’s bland observations like that that underpower this movie and make you wonder how great a writer Bryson really is. There’s never much tension in the film and no real threat. Just amiable meandering with a couple old codgers.

Come to think of it, “A Walk in the Woods” is really that leisurely stroll after all.