I am 67 and just finished four days of solo hiking in Michigan and I will have to admit that at the end I felt old. I do not feel as old today but recovery time is getting longer and I have more aches and pains at the end. My hardest lesson to learn is that I am no longer 20 years old and 15 to 20 mile days are going to have effect. Some day I will probably learn. Every time I say I am not going to do it that way again and every time I end up doing it that way again.