Plenty of ideas...
These guys might be able to suggest a
trip if you ever find yourself in Changer's ( Chiangmai, Northern Thailand).
https://chiangmaihiking.wordpress.com/Plenty of National Parks, hot springs, beautiful waterfalls & caves nearby,
easily accessible by hired scooter.
After your walk take a 2hr traditional Thai massage to sooth any aches & pains.
International airport, accommodation & food is cheap. Locals friendly.
Laos is underdeveloped & mountainous.
Cross the border into Burma & step waaay back in time..
Plenty of volcanoes to explore in Indonesia..