I'm in the middle between forty and fifty. I hike a lot, all year around (winter preferably), mostly in mountains. I do up to 40 km (it gets tiring above 30) pe

I'm in the middle between forty and fifty. I hike a lot, all year around (winter preferably), mostly in mountains. I do up to 40 km (it gets tiring above 30) per day with a backpack, around 30 km per day on skis with a pulk. To get better - just hike a lot. And consider running to improve your legs stamina and cardio fitness.