I am sick of just existing in this house. I told my wife that life without living is just death without dying. So how old is too old to get started?
I know this post is old but the advice is still the same - Your body will tell you! Work your way into and see what happens.
I got back into it some years back and ended up doing a lot of what I'd call big trips over the last couple decades. I felt like I was in my best shape ever in 2014 when I did a couple long ones, including the Grand Canyon and the Wind Rivers. Then, some of my parts started failing. Only done one trip since, this past summer. Screwed up a couple toes on that one which kept me from going back to the Winds in August.
Dealing with my 2nd detached retina in 18 months now, so I have a pretty good feel for what it's like sitting around the house-it sucks!
But I still have hope for at least one more trip to Winds - man, I love that place! Gonna try and work my way back into it and see what the body has to say about it.
I've always felt that backpacking was mostly a mental thing. Guess I'll find out how far that goes.....