There are a few great cities with mountain outdoor activities within their metro area, like San Francisco or Vancouver. Others have great options an hour drive away like Denver or Zurich. When it comes to quick access to great hiking, Hong Kong comes up on top.
I recently went on the Lantau Trail in Hong Kong, which is a subway ride away from the financial district. 45 minutes after your last meeting you can be heading up on some of the steepest climbs. While these mountains are not particularly tall, the hiking paths have a great (or terrible) feature: no switchbacks. Hong Kong has several islands scattered in the China Sea accessible by ferry or subway. Most give you a fantastic climb without distractions of switchbacks.
Many places in the US or Europe, hiking trails follow a switchback pattern to help avoid erosion of the mountain and those paths zig-zag up and down the slopes. Incidentally the moderate inclines make hiking a lot less difficult. Lantau trail (and most national parks I’ve seeing China) have steep and sometimes straight upward climbs on mountains.
Without debating the geological advantages of switchbacks, clearly the lack of them make for a great and arduous run. The climb up on the Lantau trail to the Great Buddha statue had endless hikes up and then down on the mountain ranges. (They have a gondola going up too, but this is a sports blog.)