Walking
Someone might suggest that all my interests are focused on imagination. I can agree wholeheartedly to such a statement: I live for creativity. And to give my mind some rest, or possibilities to come up with new ideas, I walk, preferably in areas that I do not yet know. Preferably in areas with mountains (which means that I'll have to leave the Netherlands). Preferably while listening to music, immersed in myself.
France is a great country to walk in. The Vercors, and the Pyrenees are both beautiful areas. However, it is frequently too warm, so you need to climb high for some relaxation.
Great-Brittain is better. Here you have the moors, not really mountains, but very nice nonetheless. There they also have intrigueing relics from the past. But for mountains you can go to the Lake District, or better, to Scotland. One has told me Wales is beautiful as well, but I've never been there.
I've only walked once in most other countries. Switzerland and Austria are both very nice. Italy and Spain too hot (for me). Belgium has got the Ardennen, which are frequently wet (in more than one way), but pleasant as well.
My last trip to Oman also provided me with some walking opportunities. I crossed a pass near the Jhebel Akhbar, which was quite fun, though a bit cold at night (we had to camp on top of the pass, as it was a rather long trip). As the climb is very hot, also with the sun shining down, you need to carry lots of water with you.