Nothing as challenging as that. Mostly, Gower, The Beacons and some Mid Wales. The area above Dan Yr Ogof, up toward Trecastle is a favourite. Llyn Y Fan Fawr & Fach are good walks. I have the Crash Sites book and I've walked to a few of those.
I wish I'd done more when I was younger, as I have to resort to drugs now. Ibuprofen is my best pal.