What things should I be doing now to get ready for the first couple hundred miles? I already have rocky hikes (creekbeds) to sort of practice on, but watching some YouTube videos shows some rock scrambles and climbing rock faces.

I'm 6'2", 225lbs. I'll probably weigh a bit less by next June when I plan to start, but should I be trying to find places to rock climb? Working on upper body and core strength? I'm already pretty used to backpacking, and will be doing a 45 mile hike next week, but watching these videos of rock climbing and rock scrambles, things I've never had to do, have me questioning if this is the right way for me to start the trail (all the hard stuff first).

Thoughts?