Mine is a decent sleeping bag. I can sleep on a hard ground with no roll mat but I can't be cold or else I just don't sleep. I always forget just how cold it can get in a tent or hall at night, but a few years back I purchased a very nice snuggly sleeping bag which made a world of difference.
Preferably I also like to take my own travel mug so I always know that I have a clean cup to hand. Not so much a comfort but I also like to have my own penknife for ease.
I'm old and creaky now and was starting to think I might have to give up camping. I really didn't want to but ached after sleeping (or failing to sleep) on the ground. But I recently bought a Light Speed FlexForm sleep mat and it's wonderful - camping is back in!