This is one of the main reasons I've stopped taking lunch at my desk. I cheat a bit, eat my lunch right before my long break while I'm getting to a stopping point, then put on my headphones, leave my desk, and wander around our campus for an hour on foot.
The music relaxes me and doesn't let me focus on any surrounding snippets of conversation, and I just let my mind wander along with my feet as I traverse our campus with no particular destination. (Our "office building" was originally an old mall, so it's huge and spacious.) This is surprisingly refreshing, and I usually find that I arrive at my desk energized mentally by the end of the hour.
The music relaxes me and doesn't let me focus on any surrounding snippets of conversation, and I just let my mind wander along with my feet as I traverse our campus with no particular destination. (Our "office building" was originally an old mall, so it's huge and spacious.) This is surprisingly refreshing, and I usually find that I arrive at my desk energized mentally by the end of the hour.