I've recently gotten back into Longboarding (like, skateboarding), and surfing. Both are relatively cheap hobbies once you get the necessary equipment, and I've been having a blast. Feel like a kid again tbh, I feel like I haven't "played" outside for years outside of some hiking and stuff
Hiking has been the biggest positive for me. I moved to Colorado just to be within a short drive of Rocky Mountain National Park. It forces you to grow in every way and then rewards you for that growth with an evermore beautiful view that fewer and fewer people can achieve. Major bonding experience and outlet for all of my other naturalistic hobbies, huge source of discipline and confidence, gives me a lot of lower body and core strength in a way that doesn't feel like working out in a gym. Plus any insurgency is like 90% hiking with weight so it's training me for what is to be done.
If there's any one hobby that will benefit someone in the most number of ways, hiking is probably it.
I carry weights in my backpack in addition to my supplies on <12 mile hikes. I'm pretty sure the military does something similar during training. Although it increases the risk of sprained ankles if you fall, it really is a fantastic workout, and I don't even feel them anymore
Working out at the gym isn't sustainable for me, but I can hike and climb all day :) I'm working toward moving closer to national parks for the exact same reason