Hi @weashloucks !
My 4 year old has a kid's digital camera (it was cheap and can survive being dropped, so win-win) and we use it for scavenger hunts. We'll make a list of 10-15 things he can look for and take a picture of on his hikes - simple stuff like 'cool looking rock' or 'spider web'. He loves it. Plus, as a bonus, since he's only taking pictures and knows not to disturb anything, it's instilling a bit of Leave No Trace ethics as well at an early age. Since it's a game, he doesn't even realize it is exercise, and just bounces around having fun.
Hope this helps!