The best holiday I ever went on was a walking holiday in the alps with a friend. Zermatt is an amazing place in the summer with its huge 4000m mountains, the Matterhorn and several glaciers which we walked across. Literally walking up a mountain does take some effort, especially when there is a train that can take you to the top, but it is more than worth it when you get there.
At home I walk the coast path with my dog and sometimes do a bit of camping as well. Also, my aunt lives in Exmoor National Park so several weeks of the summer (and winter) are spent their enjoying the amazing coastline. Having just joined the Warwick Mountains society I hope to do more walking during term time and get back to what started with DofE expeditions many years ago.