Bring a person or a group of people into your landscape shots and they suddenly get a different feel/look about them. But you have to be careful that it doesn't turn into an outdoor portrait where the person is the main focus of the image rather than part of the overall scene.
An empty shot of a forest or a mountainous landscape may be inspiring and pleasant to look at but if you add people to the shot the viewer can become more connected with the image as the person/people can help create more of a story. A sunset shot with a couple sat to one side of it will feel romantic while a rock climber scaling a cliff wall that's sat in your wide, landscape shot will create a totally different feeling.
People can also help create a sense of scale within an image for example, a backdrop of mountains suddenly turn into dominating structures that tower above two walkers or a lake stretches out for miles past a single man out fishing for the day.
As you're not shooting an outdoor portrait you don't want to pose your subjects or better still, let them know you're taking their photograph at all. Make sure they're not bothered by you or your camera and are focused on whatever they're doing before you take your shot. For more tips on shooting candidly take a look at our article: Candid photography.