Mine is very simple.
I owned an old yacht that was in very poor repair.
One day the main halyard came off the main sail and before I realised I hoisted it up the mast such that it would not come down.
The only thing to do was remove the mast, a major job which the boat yard kept putting off, or have someone hoisted up the mast.
I tried everyone, my mate the shipwright would not do it because he thought the rigging was suspect, and it was...no one at the pub would do it.
In the end I purchased brackets that could be fixed to the mast (wood) and so one after the other I installed these mast steps until I could get to touch the top of the mast.
I did this about five years ago and one leg was already playing up such that I had to lift myself up with my arms to a great degree.
But the main issue was I am sortta not good with heights so in that respect it was a massive challenge for me.The boat was on its mooring so passing boats were a worry.
However I remember getting to the top with all at the boat shed, particularly my shipwright mate, looking on.
No one thought I would do it or could do it.
So for anyone else looking it was not a big deal but the physical and mental effort for me at that age was enormous.
I could talk about other things that to someone would seem neat but installing those steps, up down and managing my fear I rate as my best.
Alex