Free climbing with no equipment.
Should come with a
health warning.
This is a lonly and often desperate activity.
It can open your mind either by showing you
that you are capable of feats that most mortals
would not contemplate, or by scattering it
in a large area as you hit the ground (messy).
Not only do you need fingers of steel
you also need balls of steel
and a heart of a lion, you need to know that
you are a god, that you cannot die, that
everything in your world, under your immediate
touch is in your control.
That said people have died from soloing when a flake
of rock has broken or when it rained unexpectedly.
When you solo you put thoughts like this out of your mind.