Since every kid is different, this may not all apply, but here's some things I came up with.
Let them enjoy the outdoors in their own way. Don't set a firm goal of covering a certain number of miles. One time we spent the whole afternoon within 200 yards of the car, and she had a blast. She picked out shiny or colorful pebbles from the creek, laid on a carpet of moss, pretended that fairies lived in a hollow tree, watched the squirrels and clouds, caught a baby turtle, picked little wild flowers, poked something with a stick, climbed through gnarled tree roots, etc. Let yourself be a kid again.
The woods are a place to play with things not allowed in the house. Like projectiles. My daughter loved to bring the slingshot grandpa gave her, and launch hickory nuts at stuff. Or the mini crossbow I made her:
https://bladeforums.com/threads/made-a-small-crossbow.1311856/ Maybe your kids like Nerf dart guns? Or a pellet/BB/airsoft gun. Or a real gun, once they're older.
Bring Field ID Guides/books, so you know what you're looking at. Tailor them to your kids' interest. My daughter always liked butterflies and flowers, so when we saw some, we'd look them up & both learn something.
To get her interested in shelter building or bushcraft skills, even in the back yard, make things for her dolls. Gather up some sticks and build a Barbie-sized lean-to or other shelter, and construct it the same way you'd build one full-sized. Make different styles, using different materials & construction methods. Let her play with it, and she won't even realize she's practicing for the real thing. I suppose you could do something similar for boys- build a fort or shelters for his GI Joes or whatever. Make traps to catch their stuffed animals. (For some reason, when my daughter would play with her dolls, there always HAD to be a villain. The evil guy could be the one setting traps.)
Pick out several important plants in your area. Ones that are useful for tinder, cordage, food, easily worked/carved/split, have medicinal properties, big leaves that can shed rain, etc. And gather them up together & make them into a toy. I always wanted to have her make her own doll from natural materials. It's not so much about the doll, but getting her to recognize these plants, and how to build stuff.