It is the temperature range in which the body doesn't shiver or sweat, but has an idiomatic sense of a place where people feel comfortable, where they can avoid the worries of the world. It can be physical or mental.
If a person said "I hate camping. I don't like giving up my creature comforts." the person would be referring, in particular, to the comfortable things he/she would have at home but not when camping. At home, for example, he/she would have complete shelter from the weather, a television, a nice comfortable warm bed, the ability to take a warm bath or shower, comfortable lounge chairs to relax in and so on. The person doesn't like giving up the material and psychological benefits of his/her normal life.